I know for the driver part since I have a 470 but a lot of people running on 64 bits didn't have any problem running the game. Try doing more research on the KOTOR forum on the Bioware website.
I just found this, you should try it. Link
[Edited by shianova, 8/23/2010 8:53:46 AM]
yea..i too have come across some who say they've managed to run both the games on 64-Bit systems with newer cards. guess i'll have to dig real deep for info. thanx shianova.