Warning! Turn of your speakers while surfing the web on Windows Vista. Windows Vista's speech recognition could listen to audio files commanding to delete files. This is the funniest security flaw I ever heard about.

A report by George Ou on ZDNet talks about the possibility of playing audio files on web sites that would issue commands that the Vista voice recognition understands. Microsoft already responded and acknowledged that this is possible and a security issue. Of course only commands can be issued that the currently logged in user has the rights to. This has the potential to become a sport though.
You should try this. Call your buddy who already has Vista installed and ask him to put you on speaker phone. Then you say "Open File Explorer, Select all, Delete, Yes".