Geforce 4 Ti4400 not as fast as expected

Hi guys. I bought a Creative Geforce 4 Ti4400. I think I have a problem somewhere, because its currently working as fast as my previously owned Geforce 256 (20 FPS 800x600 in Quake 3). I saw reviews saying FPS of 180 should be the right thing. Maybe my problem is with my PC, because its 2 years old, can it be? Its a pentium 3 600. I will try with older nvidia drivers (im using last ones ) but I dont think thats the problem. Any idea? THx uin advance!

Mhhh, it seems slow only in OpenGL apps. Unreal runs smooth on 1024x768 all detail. Nvidia demos also runs bad.