Let me first say I'm a complete newbie at this sort of thing. I'm looking to get a new one in September. My specs are: 
 
Intel Core i7 CPU  960 @ 3.20 Hz 
12.0 GB RAM 
NVIDIA GeForce GTS 450 
Windows 7 (64 bit) 
 
 
Is there anything else you would need to know? Not sure what my price range is as I'm not really sure what these cards go for. I'm willing to spend though. I'd prefer not to go overboard but I can be flexible. This is meant for gaming obviously. I just want something simple and powerful that I can run most current games at max settings with little to know issue and future games as well. Also would I have to upgrade any other components of my computer if I upgrade just the graphics card? Thanks.

I have that GPU as well xP. If your price range is roughly what I believe you mean by "flexible" then you can get a GTX460 Fermi for roughly $180 (plus or minus $20 depending on your brand of choice, mine is EVGA). Specs are usually as follows: 2gb Vram, 256-bit DDR5, Core clock: 700mhz, Shader Clock: 1400mhz, Effective Memory Clock: 3600mhz. Here's the card I used as a reference http://www.newegg.com/Product/Product.aspx?Item=N82E16814130611 It's the card I would want if I had more cash. Good bang for your buck in my opinion. (Also, could I have your old one if you get a new one :D? I'll pay shipping!) Good luck
-Ghooble

your price range is really what will dictate the card you buy. just get the best card you can for you money. i have £250 to spend on a card right now so im going for the GTX570. if i had £350 id go for the GTX580. 

your price range is really what will dictate the card you buy. just get the best card you can for you money. i have £250 to spend on a card right now so im going for the GTX570. if i had £350 id go for the GTX580. 

To give you guys an actual price range let's say I'm willing to spend from $200-400. Something like that is fine. 
 
@Ghooble said:

I have that GPU as well xP. If your price range is roughly what I believe you mean by "flexible" then you can get a GTX460 Fermi for roughly $180 (plus or minus $20 depending on your brand of choice, mine is EVGA). Specs are usually as follows: 2gb Vram, 256-bit DDR5, Core clock: 700mhz, Shader Clock: 1400mhz, Effective Memory Clock: 3600mhz. Here's the card I used as a reference http://www.newegg.com/Product/Product.aspx?Item=N82E16814130611 It's the card I would want if I had more cash. Good bang for your buck in my opinion. (Also, could I have your old one if you get a new one :D? I'll pay shipping!) Good luck-Ghooble

A GTX 560 Ti is low $200s, so get that at minimum.

Do you know the Wattage of your current power supply?

A GTX 560 Ti is low $200s, so get that at minimum.

Do you know the Wattage of your current power supply?

Ok lucky me my side panel is see through so I was able to just take a peek without having to dismantle anything. From what I could see it looked like it said "600W ATX" from XtremeGamer or something like that. 
 
Also whenever I'm looking up these cards I'm not seeing how many watts they require. I'm sure I'm overlooking it though.

@kishinfoulux: 
I have only experienced PSU's from corsair, so i can't tell if it's any good or not. But 600W should be fine for most single GPU's out there.

@kishinfoulux: 
I have only experienced PSU's from corsair, so i can't tell if it's any good or not. But 600W should be fine for most single GPU's out there.

So I guess I'm looking for something that fits following two criteria:
 
Price range: $200-400 
600W from my power supply 
 
***edit*** 
 
Actually it's possible my price range could increase so maybe something like $300-500 is more fitting 
  
Okay so I think I've settled on the GTX 580. How much of an improvement would that be over my current card? Also will I have to worry about the card not fitting or not being able to be installed in my system or anything like that? Aren't there different types of cards that only fit in certain systems or something?

@kishinfoulux: That would be a massive improvement, doubling your fps probably :P For the fitting look up the size of the card and the one of your case, check if you have enough free slots to fit in the card.

Yeah you'll be fine!

Yeah you'll be fine!

@kishinfoulux: But be careful about your power supply nevertheless, Xtremegamer has bad rep with theirs. It either works fine (30% of the time) or crashes your computer completely when handling more power demanding PCs. I do not know that from personal experience but I have been buying parts for my new PC lately and the power supplies from Xtremegamer all seemed cheap but had the worst reviews I had seen for a computer part in a long time