Well, I’m back up.
The installation went rather smoothly and didn’t take very long. I realized during the install that I had the 32-bit disk installed… and had to let the install complete because if I stopped it then my boot sector might be completely screwed.
So after installing a clean version of Vista twice I finally have all 4GB in their 64-bit glory! Seems to be running alot faster, too… but we’ll see if that keeps up once I install all the stupid peripheral drivers and other crap.