I've been playing around making some Goran wallpapers. I've only made the one at the moment, but I've got 3 versions of it so that it is suitable for the 3 most popular screen resolutions.
Choose your resolution, download the picture (mouse over pictue, right click, choose save).
Got to start button, settings, active desktop, customize my desktop, click background, browse, select the saved picture, press ok!
The wallpapers will take a few minutes to load.
Resolutions:

640 x 480
800 x 600
1024 x 768