The background: my sister's computer was so riddled with spy- and malware that she wanted to reformat and start with a fresh install of Windows. Her then-boyfriend (let's call him "Andy") assured her that he'd be able to get it done. I'm not sure whether he tried to do it himself and just wasn't able to, or if this was his plan from the beginning, but Andy actually wound up giving the computer to a friend of his to reformat. Let's call the friend Bob. Bob reformatted the computer, reinstalled Windows XP Home edition, and set up a user account... all in Andy's name, because Bob didn't know this was actually my sister's computer. Bob then told Andy that this service would cost him $100. Andy passed the computer and the charge back to my sister, who grudgingly paid it.
Four months later, Andy and my sister are no longer speaking. My sister is tired of her "My Documents" folder and all of her Office programs claiming to belong to Andy, and she's pretty steamed that Andy is listed as the computer owner. She'd like me to fix this for her. While she figured out how to change her user profile to display her own name, when I opened the Task Manager, it still lists Andy as the active user.
So: how do I change the computer's registration to list my sister rather than her dopey ex-boyfriend as the owner, administrator, document-holder, et cetera? Just changing the username on the account isn't enough; when I try to rename the Andy folder in Documents and Settings, it says that it's "a Windows system folder and is required for Windows to run properly. It cannot be moved or renamed." ...help?