So my budget is around 450 dollars and don't know what to buy, Xbox 360 or parts to upgrade my computer, so if i upgrade my computer i will have:
 
mobo-Msi p965 neo-f
cpu-Intel core2duo e4300
ram-2x1gb a-data 800mhz
vga-Sapphire x1950xt 256mb
 
So what do you think will have better graphics, and be better for gaming?

The PC.
 
You have a great PC, a X2900 would be nice, or a 8800GTX.
 
I wouldn't waste any time with the 360.

Well, the 360 is going to better for games, because that's what it's designed for. But, you can do a lot more with a PC, and you can always upgrade it when it starts getting out of date.
Prozac is right, though - you'll need an 8800GTX to get some serious gaming power (more than a 360, I think).

Not really.  360 is about the same as an X1900.
 
It also depends on the games you want to play.  There are some great games for 360 only, and some great games for PC only.

The 8800GTX is multiple times faster than the GPU in the Xbox360, but even the X1950XT would show it's advantages over the 360 in titles like F.E.A.R. and Oblivion.

Same in what way? It's just that, I've usually seem same spec PC's run slower just because the 360 is designed and optimized for gaming in particular.

My vote is the PC, you can do much more with it then just game.  But if gaming is all you really do, then the 360 might be a better option for you.

I don't know what to get because i'm both a geek and a gamer, also i don't own HDTV so i can't run the games at 1920:1080 with the xbox 360 i can only run them at 480i which is i think lame.

I probably enjoy building and refining my PC to play games more than I actually enjoy playing the games. Only you know what will give you the best experiance. Also, rememeber each system will have a few exclusive titles. Are any of these games a deal maker/breaker for you?
 
 
An afterthought: What is the deal with this tech darling junk on a website whose target audience is (in my estimation) composed mostly of male PC eunthusiast?

 
Then for the love of your geekness upgrade your computer.  

Well, it terms of image quality, an upgraded computer will far out-do the 360 if you don't have a HDTV. But, you might want a 360 for stuff like Halo, and X-Box Live (which I've heard is very good). There's also stuff like the Marketplace where you can buy add-ons for games. For example, you can buy more cars for Test Drive Unlimited on the 360.

With the PC there are allot of games that can be modded, and you'll find most of them free.

yes there are great games only for Xbox 360, if Kotor 3 is announced only for the Xbox 360 that would be a console selling game for me.

Make your decision based on what you want to play.
 
An enthusiast PC is the worst bang-for-buck platform out there. You have the WORST games (not only do most of them suck, but most of them are buggy, run like crap), and the highest price since the PC hardware cartel is composed of for-profit corporations.
 
I'd only recommend PC gaming at this time if you have specific titles you really want to play, and have deep pockets.

 
For?

 
For?
 
You want to build a PC gaming rig, it costs ~$1500.  
 
An Xbox360 costs $400.

To fully enjoy a 360, add in a HDTV too.

 
For?
 
You want to build a PC gaming rig, it costs ~$1500.  
 
An Xbox360 costs $400.
 
PC games ~$50  
Xbox: games ~$70.  
Xbox: gamming, music, slide shows, and playing movies.  
PC: Gamming, music, slide show, video editing, video capture, Music editing, free online gamming, free game mods, chatting, Forums, web browsing, typing anything, 3D rendering, Internet videos, research, Movies, Programming, Need I keep listing.
 
BTW, You can build a good gamming PC for less then $1,000 and it will be better then the Xbox 360.

 
Ermmm, a lot of console games are ported to PC. I've never had buggy problems with games (maybe you should trying buying a game instead of illegally downloading it!). They only run like crap if you don't build a decent PC in the first place, or if the software is messed up.
I built a PC for my housemate recently and I've not seen a single frame skip with Test Drive Unlimited running maxed out...

I found the HDR in TD:U a bit overblown on the 360 (as in "I can't see the friggin' road" overblown), but you can switch it off on the PC.
 
Also, you can get mods when they inevitably arrive. And you can plug in the 360 controller as well to play it, which I highly recommend (unless you have a good steering wheel).