1) Boot into XP and install the game.
2) Boot into Vista, and set the compatibility for "online.exe" and "psuoff.exe" to XP, Service Pack 2, and check the box to run the program(s) with administrator privledges.
3) Run the game.
The only annoyance with it is I had it set to run in fullscreen mode, at 640x480 at first, and it screwed up the placement of the icons on my desktop, but that's easily fixed. Time to take care of that~