Frequent Crashes on (newer) computer

Hi everyone,

I have been trying to find some consistency in these crashes. I'll be playing a game or browsing around on Firefox, when *bam* the program just disappears - occasionally Vist will 'send' the crash on; sometimes nothing happens and I'm just put back onto desktop. Additionally, I'll sometimes get an error that informs me that some background process has failed and is being reported to Microsoft.

It's strange, because I am not too convinced that this is due to a lack of memory. Occasionally I'll see that little green "DVI" in ascii font pop up in my upper right corner for a second after a game crashes, but that shouldn't have anything to do with it.

Being completely irrational, I like to presume that it's because I bought a no-name computer ("Touchmate - Better then the best!" <- spelling error included); or that I'm living in the United Arab Emirates and nothing works here: that's what I get for being so presumptuous to buy a computer here and expect it to work properly.

But now I have to be realistic and try to figure out what could be causing the crash. I downloaded memtest, then realized I have no idea how to work it; but I doubt it's a lack-of-memory issue.

Any ideas? Explorer.exe seems to be the most frequent crash, followed by firefox, and many times Civilization 4 haha.

Thanks,

Mikey

PS it is an Intel Core2 Quad Q6600 @2.40GHz; 4.00GB ram 32-bit; Vista Home Premium; NVIDIA GeForce 8600GT display adapter.
PPS oooh maybe it's something to do with the graphics card.