video driver issues.

[Skeith]

My old motherboard fried so I recently build a new machine.
the specs consist of

Board : asus P5KPL-AM SE
CPU: Core 2 duo E7400 2.8Ghz 1066Mhz bus
RAM: 4GB Kingston 1066Mhz 2.3v (bios lets me go 2.25v)
Graphics: Asus EAH3450 512MB(i believe uses the same gpu as the radeon HD3450)
OS: Windows XP pro

I am having trouble running games. They run fine but lock up after a while, game just freezes. I can alt+tab back to windows and end task so the PC itself isnt locked up.

Currently I am running the ATI drivers for the 3400 serise adaptors. Game works without locking up but framerate is poor.

The asus EAH drivers work great, good FPS and graphics but the games will lock up. Its pretty random as well, sometimes I can play no problem other times it will lock up as soon as I start to play. Never locks up on menu screens.

I cannot install omega drivers because they dont see my card.

the two games in question are
Left 4 Dead
and UT3

I had the same issue with UT3 on my laptop with the x1400 mobile card but not nearly as frequently. Any ideas?

thanks.