game Freezing

Hi.

I just got a new pc , and if i play games liek Day Of Defeat, or Counter Strike etc, or other games, my pc crashes.
I read in other posts that if i make my AGP speed 1x it wil work, but mine still doesnt work.
Is ther a way to fix this issue.
Why does this problem occur?

My Specs are:
AMD XP 1900
Soltek 75DRV5 KT-333 Motherbaord
256 DDR RAM
40 gb hdd
geforce 4 mx 440 64 mb DDR
SB LIVE 5.1