Login Screen Problem

[Dyne]

Ok, this been bugging me lately.

First, a few months ago I installed Style XP. I had the Xbox theme up for a while, and for some dumb reason I thought this "green reactor" login would look.. cool. Well, before I knew it, it uninstalled.. the OS cover came off fine, but that login screen remained. Every time I have to look at it it just gets uglier and uglier...

Now I know there's a file somewhere in the Windows folder, but I don't know what it is and I don't want to run the risk of screwing anything up. Can someone help me get it back to default, or at least give me a link to another stable demo-free program I can run to put something good-looking up for a change?