Now, Vista, where's my file actually?

If security done backwards is better than no security at all, then Microsoft are the kings of running in reverse.

You might have used some programs to edit files in "System" directories, only to wonder why the files that are there don't reflect your changes.
The answer is that, when Microsoft is unhappy about the location you edit a file in (eg: C:\Program Files (x86)\<some program>\<some file>), it creates a duplicate in C:\Users\<your user name>\AppData\Local\VirtualStore\ (eg: C:\Users<your user name>\AppData\Local\VirtualStore\Program Files (x86)\<some program>\<some file>).

Pretty sure that having 2 copies of one file is gonna be a thrill for people who want to backup their data...