I have the Nvidia 256mb 6600 and I get all my drivers from the Nvidia site. The latest one 81.98, not sure what OS you're running but here's the direct link for the 81.98 driver for WINDOWS XP - http://www.nvidia.com/object/winxp_2k_81.98.html
if you don't run XP then use ikillyou61's link.
That site has the drivers, but last time i checked they were 81.95 (not the latest drivers.) If you play games you should try getting 81.98 from www.nivida.com working.