Poor Performance in OpenGL

hi i have a Rage 128 ultra 32mbsdr on an Athlon 1.0Ghz with 256mb ram running on Windows XP Pro.
i have problems running OpenGl games on this card. for example in Counter-Strike the game jerks while running on 1024768 on opengl).
I also have a TnT Vanta 8mb Agp and Counter-Strike runs perfectely on that in OpenGl on 1024
help needed.