I've just started putting together a desktop theme for Bagpuss, any suggestions will be gratefully received, but in the meantime, here is an 800x600 wallpaper to start with, and here is a slightly better one.
The Great Cheese Race and Toad's Treasure Hunt games are also a convenient 800x600.
You could also download any of the wav files from the Intro and Characters pages.
I've finally created a (poor quality) screensaver - Let me know what you think.
Also, Gary Le Cheminant has put together a complete Bagpuss Theme and a Bagpuss screensaver, complete with sound!
If none of this is what you are looking for, there is a whole host of Bagpuss wallpaper available at the BBC Cult site
Finally, Sam has created some Bagpuss stationery to use with Microsoft Outlook Express.