In what sense? Does XP support animated desktop backgrounds? I've never really looked into it on XP, but I've got "Drempels" installed on my Win98 machine.http://www.geisswerks.com/drempels/
Some of those desktop anims look cool Although it's shareware, and the system specs a re a bit higher than drempels, because it uses the Flash MX plug-in.
Drempels just animates 2D .jpeg images. Just fill up the drempels folder with whatever .jpeg images you have and it'll cycle through, quite relaxin to watch.
A gif the size of your native resolution would be huuuuuge, and you know how much windows hates you when you try and use a desktop image that has a large file size.