You do that at your own peril. Is it REALLY worth risking having to reinstall Windows just to have a different theme?
You also really should be reconsidering this with a file sharing program like uTorrent. Who knows what else you may have picked up that could then get in. You should probably just let this one go.
I followed this tutorial but it didn't work.
This is the error i get.
What I'm trying to do..
Replace uxtheme.dll and 2 other dll files in system 32.