Apparently there was a really slick Windows XP theme that was made for the media center edition but never made it to the final cut. I think it’s pretty slick and meshes nice if you have a nice thick dark background. Note that this is NOT the Zune theme (with the ugly orange start button), it’s a completely original and signed theme for Windows XP from Microsoft, no hack required.

Step 1: Download the theme here.
Step 2: Unzip to “C:\Windows\Resources\Themes\Royale Noir” and then double click on “luna.msstyles”.
Step 3: Click on “Noir” from the color scheme menu.

Original Credit: http://www.istartedsomething.com