Texture problems?

[aabighead]

sup guys! i just installed a PNY 6600GT AGP, when i play halflife 2 games, i have this texture problem.

http://urbansounddjs.com/dod.jpg

other games works fine, does anyone know what the problem might be? my system specs are:

ABIT NF7
AthlonXP 2800+
512MB PC3200 DDR
PNY6600GT AGP
350W PSU

thanks!