I've read in other places that the backups and syncs can be affected by the USB cable used. Don't know how true this is as I only use the one that came with the iPad.
Apparently some people are using their iPhone or iTouch cables as they are already plugged in the computer and thinking they are the same (is it? I thought they were, at least looking at it anyway).
People have commented that using the actual lead that came with the iPad makes their backup and syncs much quicker.
