well, i bought a pack of new games (EA NHL, NFL, NBA, Nascar, and TW golf), but i've been having a problem with them ever since i started playing them: whenever i play them (fullscreen), after about a minute of playing time, the game will minimize and my computer will go back to the desktop screen... this will continue happening about every minute, so i have to click on the taskbar button to maximize it again... it gets extremely annoying, although NHL automatically pauses, the rest of the games keep on playing, so i'll maximize Nascar 2004 and there will be a pile up because i ran into the wall... anyway, does anyone know what that could be?

Second, i have a computer with integrated graphics ( Intel Extreme graphics 82845G) but my computer only came with PCI ports, so i can't get the AGP or PCI Express graphics cards. Could someone recommend me a good card for under $150 or so? I've been thinking about getting a Geforce FX5500 128 MB, or a or a Radeon 9250 256 MB(which is what i think i'll get) but some recommendations would be good (specifying a brand would be good too because i'll see pretty much the same card but the price will vary like 40 bucks)...
I have:
Windows XP Home edition
Intel Pentium 4 2.80GHz
512 MB RAM

I'm not sure what the issue could be, have you done recent antivirus/antispyware scans? Do you have recent graphics drivers?

The walmart near me has a bfg 5500 OC Pci graphics card for about $130 usd. It's the best 5500 AFAIK, because it's overclocked from the factory(runs faster than normal 5500's).

5700le's are also decent, but only if you can get a 128bit memory interface one, almost all of them are 64bit memory.

I had the same prob when i 1st installed Doom III ..its was my PSU

So you think the FX5500 128MB oc would be better than the 9250 256MB?

I'm thinking it's this order from the worst to best.
Integrated<9250<5200<5500<5500oc
IIRC the 9250 and 5200 are very close and the order could be reversed in some cases.