It just means your software has to be designed differently. Put data files that need changing into the "documents" section. Only use current user registry keys. Put registry info pertaining to all into local_machine during installation.

I think what may happen is that you will see developers avoiding putting their programs into "program files" and instead they will go back to the old ways of storing the lot in their own directory e.g. "c:\games\my game"

I think Vista may end up biting M$ in the bum.

Having said that I have a few friends who use Vista on a daily basis and they are total converts. Then again they develop in .Net