In the future, use programs like Sandboxies[1] so that shit like this doesn't happen. As the name implies, it sandboxes programs you run inside it so that they can't touch your filesystem or registry (by default, they have read-access, but not write-access; and changes programs make will be transparently redirected inside the sandbox).
And it also has convenience features that allow you to easily merge-back your changes from the sandbox to the live filesystem. For example if you run a bit-torrent client inside the sandbox, and Sandboxie detects it tried to make modifications to, let's say your "Downloads" folder in your user-profile directory, it will give you a nice little prompt to let you ignore or merge the changes to the live filesystem.
http://www.sandboxie.com/Never trust software unless they are from a source that can be vouched for.
