Boot Camp "Video Memory" Help

I recently downloaded windows xp onto my macbook using boot camp. Its very cool, but I got it specifically for gaming. I got the vice city exe. and the installation goes smoothly. Then when I click on the actual game it says not enough video memory. Now, I have leopard and boot camp was already installed but, I'm a little confused about this whole download drivers thing. If anybody could help at all please do feel free to.