Jealous of the awesome Windows 7 wallpaper slideshow feature? You might not realize that Microsoft released a similar feature for XP years ago, and it also works on Vista. It’s hidden inside their "Winter Fun Pack", but the Tweaking with Vishal site has you covered with instructions on how to get to it.
Get Windows 7’s “Desktop Background SlideShow” Feature in XP and Vista Using Microsoft’s Official “Winter Fun Wallpaper Changer” Powertoy [Tweaking with Vishal]
I feel awesome, I have this on my old XP machine already.