Ok here's my full PC specs.

Intel Core 2 Quad at 2.40 Ghz
4GB DDR 2
Nvidia GeForce 7100 / Nvidia nForce 630i (2GB of Video Card RAM)
Windows Vista Home Premium 64-bit
Direct X 10.0

OK, it's definitely your graphics card. That's probably an integrated one.

Other than that, your PC's fine, but unfortunately most games are very dependant on the graphics card. With some $100/100€ it will become quite a good gaming PC though, and with $200/200€ even better. Still, you will do fine with $100/100€. That is, if you're willing to upgrade. And if you are, you should also check your PSU to see if it provides enough power.

alright thanks Zkuq, Ill look into to upgrading my video card soon enough, I have a 300W PSU so Ill prolyl haev to upgrade that as well

Yeah, although watts don't mean everything, I can pretty much tell that even a high-quality 300W PSU can't be enough. Try to go for something with enough amps in the 12V+ line (or lines - if there's several lines, it's almost as simple as adding the lines together). Anything over 30A should be sufficient unless you're going for high-end cards, though more is better and makes future upgrades more likely to be possible. Let's make that at least 34A-36A at least, instead of 30A, just to be sure. I, for one, have 15A+15A (30A) for my GeForce 8800 GTS 320MB and my PSU was probably only barely enough.

Anyway, it'll cost more with a new PSU as well... But I guess that's not a surprise. And try to look for a decent manufacturer.

As for the new card, right now I guess GeForce 9800 GT/Radeon 4830/Radeon 4850 might be pretty good low-price cards. Not completely sure, though, as I've been "out" since DX10 came out.

Tell me how graw works when you get it. I played it for 360 when i bought my console but... i forgot about it with gears and r6v.

Yes, those are indeed the current sweet spot. Out of those the HD4850's probably best: it can play any game save Crysis on high to max settings at 1600x1200 resolution or below. And it's only $100. Nvidia just isn't competitive in the sub-$150 space right now.

@OP: Yes, it's definitely your graphics card. Buy a new one.