Do you have it installed on the same drive as the operating system? In Windows 2000, I couldn't even get it to install until I put it on the same drive. You might also kick it down to 16 million colors (this doesn't seem to degrade the 'look' of it) and uncheck 3D acceleration (keep 3D animations checked) in the BG II configurator. You could also try turning down the frame-rate in the Gameplay tab. Hope this helps.
------------------