Hi there. I am a gamer and I play counter strike, warcraft 3, diablo 2, and so forth. Sometimes playing games like these can cause your system to crash. Sometimes you can't even play it because of a reason. These are the thins you should always do if you are having problems with display.
1.Go to Windows Update and Install Service Packs and DirectX 9.0
2.Install the latest drivers for your video card company. (Geforce = www.Nvidia.com)
3.Always have a lot of RAM. I suggest 255, but I like 512 better :P
Sometimes these problems can be fixed by reinstalling them. If you crash while you play(happend to me couple of time when using WIn Me), always get a Anti-Virus Scanner and do a standard scandisk. To remove registry changes and ads, you should download Spybot and AdWare.
If you are experiencing slow gameplays, disable unneeded start-ups (schedules, task managers are unneeded.) and try defragmenting the computer so that your computer can run smooooooothly.
For Win98/ME users, go to Control Panel, Systems, Virtual Memory, and type Min = 1000 Max = 1000. This should improve graphics performance. If you mess up or you see a blue screen at start-up/boot up, don't panic. Boot in Safe Mode and check the box where it says "let windows do the virtual memory blah blah". Then reboot.
If you're filthy rich, try to get one of the best video cards out there. ATI Radeon 9800 is a good example. Be sure to get a nice motherboard if you want to get those expensive video cards. Most of those good ones are 8x AGP, and old motherboards such as P3 Motherboards may not support it, so it is two times slower/crappier than its supposed to be. Mines is 4x, which sucks a lot.
If you're a extreme gamer, and still cant play games, try reinstalling your video card. If you're really desperate, reformat your Windows.
THESE ARE WHAT I KNOW so correct me if im wrong :P (All of them should be right...)