Video resolution problems in games on Inspiron 6400

Hello everyone, I recently purchased an Inspiron 6400 preloaded with Windows Vista. I'm mostly happy with it, except for the following problem. When I try to run older games, namely Star Wars: Knights of the Old Republic (but also other games), i experience a problem where the screen doesn't resize the resolution properly. Instead of scaling the resolution up or down, the contents of the game simply "hang off" the right and bottom of the screen, rendering much of the gaming field unviewable. My notebook has the ATI Mobility Radeon X1400. I've tried to solve this problem by switching from the native drivers to the ATI Catalyst beta drivers, but to no avail. Anyone have any ideas? Thanks very much. ~Seth~