I was having problems getting GIMP, GAIM and GTK+ to play along together in Vista Ultimate. After a couple of hours of frustration, I downloaded and installed Portable Apps Menu.
It installed without a problem, as Admin, and I was able to Sudoku and XAMPP installed as well.
GAIM has a problem with the display of the fonts, not sure if that is a problem with it getting the font info from Vista or a limitation of Beta5. Beta6 didn't have the problem.
GIMP and everything is now working just fine.
Thumbs up!
Psijudge.