These are freely available on Disney's web site, but they are a *pain* to get to each one. Here you can get to them all from one page.
Left-click on an image to see the full size image.
To save the images to your computer, Right-click on the image and choose the option to Save Link As (Firefox) or Save Target As (Microsoft IE).
To set the images as your desk top background, Right-click on the image and choose the option to Set As Desktop Background... (Firefox) or Set As Background (Microsoft IE).
Buddy Icons on this page are actually full-sized. For the links to the screen savers, you should opt for the right-click save option.
If you want to download them all at once, in an automated fashion, check out the Firefox addon called Down Them All!