Low FPS with Half-Life in openGL

first off, heres my system:

PIII 600
winfast GeForce 2 GTS 32 DDR
SB live 5.1
20 GB ata 33

the most recent detonator 3 drivers from nvidia’s site. the problem i have is my average fps is 25 at 1024x768, which is way too low, i should be at at least 72. when i run the game at 1024x768 in D3D, im at 72 fps. ive tried formatting and reinstalling everthing from the OS to half life and all the drivers. someone said it could be the video card. im planing on taking it back and getting the same card and seeing what happens. just wondering if any of you have seen this problem, or know what it could be. my friend has a brand new dell which is:

PIII 866
Geforce 2 GTS 32MB DDR
20 GB ata100
running the same detonator 3 drivers

he gets 72 fps ALL THE TIME, doesnt matter if theres 20 guys on the screen, explosions, lighting effects, etc. we have very similar system specs so im pretty sure i can get 72 fps also. PLEASE HELP!!!