Vista x64 has worked with all of my games.
However, if you subscribe to something that uses DRM (Gametap, Real Rhapsody), install XP or Vista x86 on another partition as the drm drivers/software aren't fully compatible with Vista x64 yet.

After going through the boot camp wizard (it'll walk you through partitioning and stuff), stick in your vista dvd, enter your key and watch it install.

Be sure to update Boot Camp though if you haven't already. The new version includes signed drivers for Vista.