I've managed to make the webcam my desktop, by selecting Destop Properties > Customise Desktop > Web (windows XP) and pasting the link into the box. Can't make it update automatically though, have to click on syncronise every time you want to see it update.
To auto Refresh you just need to create a local HTML page with an auto refresh Tag at the Top of the page to force a refresh every 60 seconds.
HTML:
<meta http-equiv="refresh" content="60" >
<img
src ="http://www.nuerburgring.de/fileadmin/webcam/webcam.jpg"
>
Save the above Code to HTML file and store it somewhere on the computer. Then add the path to that file to the active desktop not the webcam path you've used before.
To save as HTML open Notepad paste code into it hit
SaveAS, change the S
ave as Type to "
All Files (*.*)" and type the File name as
xxxxx.html
That should work but i can't test it as i've only got a Vista Boxes in my current location.