I think Mandolux.com must be the site with the most tasteful desktop wallpapers on the net. Really hi-res too and many panoramic ones intended for twin monitors side by side (one day maybe!)
I just installed the MiX theme for windows which looks trés sexy, and I have a fresh install of XP. Now if I can just keep from clogging it up with a million useless progs that never get deleted or uninstalled...
My desktop currently looks like this - very restful methinks