BIOS error?

[Play]

I've been recently playing some games that have biiig machine requirements (HL2, Sim2, Flatout...etc). My comp meets the minimum requirement stated in the readmes, but the games are stuttering, freezing, locking up after 2 mins of play, craching to desktop with no error messages, or not even start. My conf:

AMD Athlon XP 1700+
ECS Elitegroup K7VTA3 (3.1a) with VIA KT333 chipset
GeForce4 MX440 64MB +TVout
256 DDR
CMI 8738 4 channel sound (integrated AC97 disabled )
40GB Maxtor HDD
Win XP pro with SP1 and more updates installed (no SP2, it sux )

For "earlier" games (Sims1, GTA VC, Hitman x) there was no problem, or not recognisable, but newer games has some huge problems to run. I tired everything. I have the latest drivers for video/sound, defraged HDD...etc. But games, and some programs still refuses to run correctly. Sims 2 and others run smooth on my friends machine that is similar to mine, he only has Intel proc and MSI board.
I downloaded some monitoring apps, but the proc and the case is in the normal temperature scale, the fans working perfectly, voltages normal.
I got some memory apps, but the memory is not even 70% used normally...
Enlarged the swap file to 500MB.
My problem still stands. What on earth can be the problem????


Please help!