I cannot really help you re: Vista... For the simple reason that I refuse to have any more to do with it except to advise people on the best ways to remove it.
I have seen other examples of older applications being installed (with difficulties) in Vista... Then, poof they are gone...

btw... I am going to move this thread to the BearShare forums.

Please look for the threads and posts in the BS forums for info on downloading and installing the last clean BearShare beta... I am sure your friend will like it... Assuming Darth Vista allows him to do so !

Screw Vista