not really a security question but....

I recently put a Geforce 2 mx vid card in my linux (running RH) box and now the only video mode i can run is 640 x 480 x 8.....ive tried just about everything i can think of in Xconfigurator (custom vid card and monitor and closest available preset vid card and monitor options) but if i try to increase color depth or resolution it either hangs or just goes back to the terminal and says it didnt work. ive also installed every xfree86 rpm i can find and tried it, none worked....any ideas?