I have an HP Pavilion 9600 that had a nvidia tnt 32mb video card. When I upgraded to a Geforce 2 GTS card the performance dropped. I made sure I had the latest drivers but that didn't make a difference. The tnt still performs better. I thought it might be a problem with the card itself but I tried it in a different computer and it worked great. I also thought it might be that the bios needed to be updated but when I try to do that it says that it can't because a memory manager is present. The current bios date is 02/2000. Please help!!

Pentium 3 600
128mb ram
40gb 7200rpm maxtor hard drive