I had purchased a voodoo2 for my 233mmx, had it installed and was able to see how wonderful it worked with my games. I then got greedy and decided I would be better off with a Banshee(i have 2Megs of 2D memory-not upgradeable) so I uninstalled the Voodoo2 and put in a Guillemot Maxigamer. The 3D is ok but I don't really see a difference with the 2d. Is there someway to tell if it is working correctly (my previous 2d is onboard and all i can do is diable it)? If its working and this is all it gives me I will probably go back to the Voodoo2 or a TNT card.
You should make sure all of the drivers for the s3 card are removed from the system, and then install the drivers for the banshee card. When you say you dont see a diff, what do you mean? Is the picture quality the same? Are the video modes and refresh rates the same?
It is possible that you monitor is a limiting factor too, what type of monitor do you have??
Try disabling the s3 chip in the bios, if you cant, goto system in control panel, and goto device manager. Look for the s3 listing and double click on it. Find the little box that says "disable in this hardware profile" beside it. Now check the box and reboot system with the new card in it. It should ignore the s3 card and install the drivers for the new one.