I've decided to upgrade my AM3+ rig to Vista, despite having to do a clean install of 64-bit Vista (to be more specific).
This means I can use all 32 gigs (with only 16 gigs usable by Windows), and still be able to play UT2004 or Quake 3 without a hitch for instance.

The base hardware hasn't changed from before, all I did was upgrade the OS.