I happened to check out the Vudu website tonight, and as I browsed through their selection, I was impressed by the rather large amount of Disney films they offer for rent or digital download. They have almost 400 titles, including both new favorites and a sizable number of classics, both animated and live action. It's not a perfect collection, but it IS worth checking out.
VUDU - Watch Movies - Collections - The Wonderful World of Disney
You can view trailers for some titles, and 2-minute previews for most, before deciding to buy or rent. I was particularly impressed with the image and sound quality of the little-seen 1961 live-action comedy Moon Pilot. It looked and sounded outstanding for its age.