The Xsplash I'm talking about is called PackoXsplash HD and comes in two versions:
To install it, simply extract the archive to
/usr/share/images/xsplash(make sure you open Nautilus as root, by using the following command:
Of course, you can also use one of the images in the archive (the one suited for your screen resolution) as your wallpaper.
Download PackoXsplash HD