I am looking to buy a new monitor. Actually a monitor. I am currently using my HDTV to play pc games on but the tv tray + extra ikea bookcase shelf combo has become a bit annoying. 
 
So I'm gonna buy a monitor so I can use my PC at my desk like a "normal" person. The tv I have now is 1920x1080. I had a monitor that was 24" 1920x1200 but I gave that to my girlfriend once I got the TV.
 
Basically it comes down to cost for me, I think a 20-22" would be plenty big if I'm at my desk and it would be cheaper. 1680x1050 seems like plenty, but I've never actually played any of my current games at that resolution. I cant image a difference to be honest, but maybe there is. For example in a modern game like Mass Effect would I even see a slight difference. In concept wouldn't a lower resolution also result in more fps, even if it is minimal?

You want a lower resolution for gaming, because then you can achieve higher quality settings. The difference in FPS pretty much scales to the number of pixels 1,7Megapixel  at 1680x1050 vs 2,1 Mexapixel at 1920*1080.
 
By that logic at 1080p presolution your PC renders ~18% less FPS compared to 1680x1050.
 

The difference is quite noticeable especially when you are up close to the monitor unlike the TV.
It will be even more pronounced by the large size monitor you are going for. 
The difference between say 1920x1200 and 1680x1050 to me at least is huge.
Performance wise bigger resolutions increase the processing requirement by a lot as well. Higher resolution uses up much more resources and lowering it down a tier is a huge FPS improvement most of the time.
 
For example my laptop runs all recent games at 1920x1200 with good to decent fps, but if I try to play Crysys it will have horrible fps at 1920x1200, but at 1680x1050 it's playable but then playing Crysis kinda looses the point because it's not as pretty anymore.

Well take a look for yourself then. X1050 is a 16:10 ratio, X1080p is 16:10, it's more squarish than before which is rectangular. I would say it's alot like your X1200 monitor but smaller. 1080p content like movies will look aweful at X1050, it doesn't fit at all, even console games will look squished. It's okay, alot of ppl really thought I posted good screenshots at that rez before, however I find I like 1080p more. I also use a HDTV as a pc monitor right on my desk, I still like it more than a pc monitor since I did ran a X1050 rez. You will get more fps, slightly more, not that much though depending on the game.  
 

http://img813.imageshack.us/img813/9070/re5dx102010011017174770.jpg 

http://img816.imageshack.us/img816/7901/re5dx102010041018270897.jpg
 
X1050

  X1080 (can't see the weapon thing on the right, it's much wider)

Resized, look at the aspect ratio 
 
taller

wider (usually it's much wider than the screenshot above, not sure why it's not, you get the point it's rectangular)

       
I still recommend you get a 1080p monitor instead with hdmi, they make 1080p monitors and get a 24" monitor. Or else get a X1200 rez monitor again for pc gaming. X1050 is outdated and you don't get a sharp screenshot, to me anyways it looks a bit blurry on my 1080p display.

It doesn't really matter as long as the resolution is appropriate for the size of the screen and you run your games at the native resolution.  A low resolution spread over a large screen isn't ideal, obviously.
 
I think AA (or more AA) is typically a better use of your resources than just having a massive screen and a massive resolution just for the sake of it.

@Jimbo: Highly disagree with your post. 1080p is wider and has more pixels. It's not because of massive screens or whatever you said, it's about 16:9 wide or 16:10 squarish. Having more resolution means having more pixels, more pixels = more detail. If you add AA to it with that resolution, it would look even better still than a low rez with full AA. I tried crysis on 720p and it looks aweful regardless of how much AA you use at that rez. It doesn't give you massive screens, if you are seeing my screens above, those screens has exactly 1920X1080 pixels to make it that size. Maybe you are using a crt monitor or low rez monitor to say that because they look normal to me on my 1080p display. My screens will look smaller to someone who has a x1200 screen.   
 
 
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Let me try it again, maybe this would make a better point of the shape of the monitor for the op. Do you like a squarish screen or a wider screen? Look at the games and maybe that would help you decide. I rather go with the wider one with more rez, the better. AA isn't important as resolution, you can always add AA if you want to afterwards and it would look better than trying to sharpen low rez which is unimpressive.
 

More resolution is good, but games should be played at a LCD monitor's native resolution.  Don't get too high res of a monitor or you'll have to turn down in-game settings.  However if you have excess power you can always add AA.  Just don't do something stupid and buy a monitor that your GPU can't support properly.  It's easier/better to make a lower res screen look better than take a high res image and scale down effects.
 
You also might want to consider screen size & resolution when thinking of readability for regular net usage / other computer usage.

I guess it really depends what youre going to do with your monitor. I guess the standart nowadays is 24" (or 22") 1920x1080 because of the full hd. Since u dont watch any movies or play console games on your monitor I guess u dont have to get a 16:9 one. If you wanna go really cheap you can get a 1650x1080 22". But it really depends what u wanna do with that screen. If you work alot on your pc maybe that extra relsolution would pay of or you wanna spend more money and get an improved panel (The cheap ones all have TNs which have some deficits, like unstable backlighting and color patterns). 
 
Edit: Btw. this site is great for monitors:   http://www.prad.de/en/index.html. They also have a decent buyers guide to help you out. Depending on where u live, u might wanna look at this monitor:    http://tinyurl.com/35oqsom

once you go big u dont go back

Eh,I have a CRT that runs at 1024x768 and I play all of my PC games on that. My other alternative is an HDTV that runs at 1360x768 but refreshes at 60hz (rather than the 85hz my CRT runs at)   
 
Different strokes for different folks. Refresh rate will always be the #1 concern of mine.

I guess I should add that I have a pretty good GPU, XFX HD4870. I can run a game like dragon age or mass effect at full settings. Crysis I can get a constant 28-32 with texture detail turned down one notch and AA only at x2 at 1920x1080. So running the games isn't really my issue. I should rephrase my original question.
 
At the same settings (texture detail ect) can you see a noticeable difference between a monitor running at 1920x1080 versus 1920x1200 versus 1650x1050? Realistically, not by starring at screenshots.
 
then another question. How much more of a FPS and AA boost can one realistically expect from going from a 1080p resolution to 1650x1050? Any one tried lowering their resolution and checking with the FPS? I think I will the next time I play a pc game.
 
I think I will look more into a 1080p monitor, I think I'd rather have a 16:9 image over a 16:10 to be honest after using my HDTV for a while. I've been looking at this one for a few days 
 http://www.newegg.com/product/product.aspx?Item=N82E16824254044  

I have a Benq HD2420 monitor, brilliant screen, highly recommended.

Uploaded with ImageShack.us

    
http://img7.imageshack.us/img7/7449/crysis2009031109083843.jpg

   
http://img9.imageshack.us/img9/8272/mirrorsedge200903111159.jpg

@TMThomsen: Your totally wrong I totally disagree with you 100% and those aren't my images. Those are my friends images, I have permission to borrow them. They are running for the first screenshot, two gtx 260, the other ones are running at gtx295. Their anti aliasing settings are variable. Also your probally running a X900 rez monitor and you can't see anything good about them, they look very clear on my X1080p 40" display.  
 
Lower resolution and AA? Lol, whatever, that's equlivent to saying a console running more AA looks better than pc games with 4X AA. That's not true, get real, lower resolution = less pixels = the suck. I think 1080p is just about right, the X1200 looks a bit large and different, like overly exagerated, still more resolution is usually better.  
 
What resolution are you running your display right now? I'm guessing it's a crt monitor, how can you possibly see the screenshots? I want to know because I don't think you can fully see it because your display is downscaled to a lower rez than what it can display. Trust me if you seen a X1200 rez monitor playing a pc game, it's breath taking. Yet of course, you need a powerful gpu.
 
You think this 16XQ is jaggy? You can see textures to a point where no other version of the game can even display such high rez textures. High resolution = more details for high rez textures.  
  

http://img9.imageshack.us/img9/8848/mirrorsedge200903111205j.jpg     
 
just look at the wall, you can see every texture, it's shiny and it's perfect. Maybe too much detail, that's the problem.

After looking at all the options I think I am going with this one.
 
 http://www.amazon.com/dp/B002ZVCGXQ/ref=asc_df_B002ZVCGXQ1138473?smid=ATVPDKIKX0DER&tag=pg-448-75-20&linkCode=asn&creative=380341&creativeASIN=B002ZVCGXQ
 
Pretty much everything I want. Thin, light, HDMI, audio out, led so low power comsumption. Probably better ones on the market for a bit more $ but this fits my needs perfectly.
 

@MrOldboy: It tilts backwards a bit btw, like a laptop and that ring thing on the back holding it won't make the panel go vertical or it will fall over on the front. However it's not a bad choice considering the price, that's honestly really cheap for a monitor. Just thought you should know because I actually was looking for a display for months, that was one of it and I just ended up getting a thousand dollars hdtv because I could find a monitor that suited me perfectly. However if you can get used to the steep angle on the side, then it's still a good monitor, since there isn't a normal stand, it's going to be very low on the table.  

I also want to recommend this monitor, I know it's more expensive, however it's just a suggestion so you know what's out there for led monitors. With this monitor you also have a stand. 
 

http://www.amazon.com/Samsung-XL-2370-1-23-Inch-Widescreen-Monitor/dp/B0030CFC94/ref=sr_1_1?ie=UTF8&s=electronics&qid=1276491444&sr=8-1    

" @nabokovfan87: No, Samsung monitors have shaky stands. I know because all my Samsungs are like that. :(   Great monitors, but those damn stands! I'd even be willing to pay slightly more if they invested in better ones! "