Through Rokus.net (which also has lots of useful snippits of info) I found this link on Technet which provides information on the steps needed to copy WSUS data from one server to another. It's actually intended for deploying WSUS on a disconnected network, but given that most of the demonstrations I give (and I think I'll use this for my blogcast series on Infrastructure Essentials) are "disconnected", most useful especially as I already have all the updates downloaded on a WSUS server at home. Should be simple to put them into a Virtual Machine using this info.