Setishock? I have no idea what thats about either...
Anyway, yeah, thats a good program. Untick it to delete any settings on programs you don't want to get rid of though, as its so good, it will wipe settings from MSN Messenger, and programs like that that you've set, like fonts, etc if you don't look at what your deleting first.
Its a really good program though, and don't let this put you off as I did it by mistake, and just had to change settings for a couple of things, but i'll kno for next time.