I just installed the latest version of the nvidia driver from their website, everything is correctly configured(nvidia driver and their glx is getting loaded) and is working well, but I cannot get a 32bpps color buffer visual.
When I use glxinfo, the only visuals I get uses 16 bpps for the color buffer.
glxinfo shows the available modes in the current color depth. I do not know of any way to change color depth from a X program so you have to edit your XF86Config-4 file. If you temporary want to use another depth do I belive that you can pass a parameter to startx.