Ok, guys and gals, again, I need your help.  
  
So, how do I do it? 
I was thinking to connect the 360 RGB cable to a RGB to S vid adapter to my graphic card and use some software to show it on the monitor. Is that even possible and if so, what software do I need? 
 
If there's a easier way, please let me know. 
 
Thank you =)

You will need an Xbox 360 VGA Cable. They're roughly $20, I would say. Look in local retailers or buy one online. It's basically a VGA Cable, with a different connection at one end which goes into the 360. Plug the other end into the monitor and screw it in, and everything should work fine from right now. Note that the display might look a little terrible till you get into the System Settings menu on your Xbox 360 and fix it, by upping the resolution to the highest your monitor will allow and the like. That should be everything done. I made the switch from SD to a monitor a well, and if it's one you're in a position to make I highly recommend it.

What Mp44 said. Once you go monitor you don't go back. 
 
Although I did go back.. when I got an HDTV for the end of my bed. But that's besides the point.

I live in Croatia, retailers don't have much, and the stuff they have is expensive as hell. I just saw this cable you speak off at a retailers web shop for 55 $. And here, thats a lot! I can get a 360 wireless controller for the price of that cable. 
Is there an adapter to convert the original 360 RGB cable to VGA?

" I live in Croatia, retailers don't have much, and the stuff they have is expensive as hell. I just saw this cable you speak off at a retailers web shop for 55 $. And here, thats a lot! I can get a 360 wireless controller for the price of that cable. Is there an adapter to convert the original 360 RGB cable to VGA? "

You have a hdmi xbox360? If you do, then you can get a hdmi to dvi cable.

HDMI is the simplest option if both your system and monitor have those ports, although audio might have to split off if you don't have speakers built in. Otherwise Vitor has the best advice, try some HK sites that do electronics, they are usually cheap, but the quality might not be the best.

Is there even a such thing as an RGB input to a VGA Output adapter? I can't even find it googlin'

I live in Croatia, retailers don't have much, and the stuff they have is expensive as hell. I just saw this cable you speak off at a retailers web shop for 55 $. And here, thats a lot! I can get a 360 wireless controller for the price of that cable. Is there an adapter to convert the original 360 RGB cable to VGA?  

Damn man, that is insane o_O

Try finding a web retailer like eBay and ship it over. There are some unofficial VGA cables which do a perfectly good job, so don't be lured into thinking it must be a Microsoft branded cable. It doesn't, and mine is not. If you can find any VGA Cables that have an end for the Xbox 360 they'll work flawlessly, so that might save you a little money. There are also things like the 'Grand Hand View III', which theoretically might work, though I only know for certain they work with capture cards and VGA monitors. It's not impossible you could use a Grand Hand View to connect and convert the signal, but it'd be highly experimental, and if you live in Croatia it might not be worthwhile to even try considering the pricing of everything.

Unofficial Xbox to VGA adapter cost me a few quid on eBay. Comes with stereo phono outs connected. Works like a charm.

Hey there! I had this exact same question a few weeks back myself. Moving into a dorm room at college and not having a TV but buying a 360 and assuming it would work on a DVI monitor automagically didn't work out so well at first, but, with a bit of fiddling, you can make it work! 
 
First of all, this is assuming you have a HDMI-out on your 360, and a DVI-in on your monitor. If you do, the snag yourself one of these for a mere $8.37 + shipping. Now you've got the video covered, but what about the sound? 
 
The method I'm going with, but cannot confirm 100% that it will work, is buying this Xbox 360 Hi-Def Audio Adapter thing. Because I don't know if you know this, but HDMI shoots out both video and audio, and by converting HDMI to DVI, you're losing the audio in the process. This thing will plug into your normal Xbox 360 A/V-out jack, but instead of giving you the all of the colored cables, you get just good ol' red & white RCA and an optical audio, which is something I know literally nothing about. From the RCA audio-out you can put it into your speakers or whatever, but you might need some converters depending on what kind of speakers you have. 
 
While this all is shipping I ended up going even further than this. I already own a nice LCD monitor and a decent set of 5.1 computer speakers, so I devised a series of switches and cables that will give me the ultimate dorm setup on the cheap: with one monitor and one set of speakers, I'm going to be able to plug my PC, laptop, and Xbox 360 in all at once, and switch the audio and video going to the monitor and speakers between any of these three at will. I might write up my exact purchase list and such if anyone's interested, and when it comes in the mail in a few days, I'll probably do a blog post too :) 
 
EDIT: Also, if you want, you can just get a USB A/V capture device, but I strongly suggest you don't. This is what I've been using while my stuff is shipping, and it sucks massively. There's a noticeable input lag, and the video quality is absolute shit... admittedly, this was a cheap Radio Shack thing, but if you're going to invest money in a setup, I'd advise to do it my way.

I don't have a credit card to buy online. I just found a used one for 22 $, called the guy, I'm gonna pick it up in the couple of hours. Thanks all. 
 
But, now I'm wondering, is it possible to connect it like I said? Trough S-vid?

360 VGA cable, HDMI? then HDMI to DVI or an VGA or DVI selector box that accepts component inputs.

Make your own VGA connector for cheap: 
http://www.engadget.com/2006/11/14/how-to-turn-a-standard-xbox-360-video-cable-into-a-vga-cable-fo/

For sound, there is an av (red white av cable) to stero adapter (3.5mm) for pc speakers.

"

For sound, there is an av (red white av cable) to stero adapter (3.5mm) for pc speakers.

"

Use a VGA or HDMI to DVI cable.

Hey guys, I bought and hooked up my 360 with the official VGA xbox 360 cable. It's GREAT but if you look reaaaaally closely, it looks like there's a silhouette of the real picture slightly off the real feed. Is that normal and what can I do to get rid of it because it's getting on my nerves.

" Hey guys, I bought and hooked up my 360 with the official VGA xbox 360 cable. It's GREAT but if you look reaaaaally closely, it looks like there's a silhouette of the real picture slightly off the real feed. Is that normal and what can I do to get rid of it because it's getting on my nerves. "

Did you set your Xbox 360 Resolution and Refresh rate to match those recommended for your monitor ? Also, since your monitor has two entries, I guess you still have your PC entry connected on the other port, you may want to try to unhook the PC feed to see if it doesn't create interferences.

As a quick update, I got my audio adapter in the mail today, and it works awesomely. If you have an HDMI-capable Xbox 360 and are willing to possibly swing by RadioShack or what have you to pick up a RCA red/white audio male to 1/8" male (or female, depending) cable, depending on what kind of speaker setup you have, my above method works great for getting you basic audio to your computer speakers and video to your computer monitor from your Xbox 360.

My SD television was incompatible with my 360 so I got the VGA cable and it was the most awesome thing ever. Nowadays I play on a big Plasma TV, but I think I actually prefer the smaller size of the LCD computer monitor, plus it's harder to notice graphical inconsistencies / jaggies because the pixels are closer together. 
 
If you keep unplugging the console from the monitor to swap with a PC; eventually the pins in the end of the cable will break (I can't remember if the pins were on the cable or the cable-sex-change adapter).