Is the mod official or user created? And why run in opengl? Should not be any faster.
9500gt is a pretty weak card, it may not have some features the mod needs to run, another card may be a good thing to try.
zombie mod is a plugin .. counter strike supports display 3 modes 1)opengl 2) software 3) D3D .. my game works on software mode , but the display sucks .. opengl is better .. i want to play it on opengl ... previously i played zombie on opengl .. dont know what happened.. now its crashing only if try to join zombie server .. i read many thread they say update driver .. and i did it still its crashing .