XPize

XPize screenshots

It replaces the bits in Windows that didn't match XP's style with bits that do
Desktop
XPize 4.7 beta : Desktop

Alternative downloads

XPize Lite
5.6
FREE
It allows you to change hundreds of aspects of your operating system.
Canada Theme Pack
1.0
FREE
It'sa fully integrated collection of graphics modules of all things Canadian.
PS3 Theme Creator
2.0
FREE
An easy to use tool to view, create, generate PS3 Themes in realtime.