Back up to Airdisk?
 

I have a hard drive connected by USB to a hub attached to my Airport Extreme. It shows up in Finder but not as a destination in SuperDuper. I've seen posts re creating sparse images etc but would appreciate a more detailed explanation (if in fact that's the way to go - and if not, what is). Thanks!

Please see "Backing up over a network" in the User's Guide and the "Airport Disks" post at the Shirt Pocket blog...

Thanks. I think that convinces me not to try this approach!