Gaming PC? I'd DEFINITELY upgrade that video card. I'm not sure that would be able to run Crysis at any setting... My friend has a video card that is supposedly about 1 1/2 times as powerful as that one and it would have to run Crysis on low with a small resolution to get a good frame rate, I think.
Also, I've heard that this
is much better than Arctic Silver 5.
I probably wouldn't go any
weaker than this
for a video card, and even then I would prefer a more powerful one.
If you want a graphics card that can run Crysis Warhead on about 1080p, very high, 4xAA, 16xAF, at about 30 FPS, I would probably go with the GTX 460 768MB
at the bare minimum.
You probably won't need more than 4GB of RAM for something you'll just be gaming on, btw.
But if you're going to be doing a lot of RAM extensive multitasking, you should go with the 8GB. (3d artwork, video editing, etc., etc.)