I got this off Steve’s Place In Space, (great blog), the Windows XP Royale Theme, which originally came with Windows XP MCE 2005. Its now free, it is awesome theme that is smooth and adds some attraction the Blue Luna Theme that comes built in with Windows XP. I have Windows XP MCE 2005 on another computer, and the actual name is "Energy" not "Royale" when you enable it under Control Panel > Display > Appearance > under "Windows and Buttons" > Media Center Style.
I came across this and thought I’d pass it along. It’s the Royale theme for Windows XP that includes a new user interface as well as some new wallpapers. The theme is shiny, glass like and it also changes your start menu colors. It’s just a spiffy new look for all us XP users.
How to change themes in Windows XP: