Migrating WSUS to a new server without downloading updates
Mark Wilson has written an interesting and comprehensive article on his blog which he's kindly given me permission to reproduce here. It not only talks about migrating the content and configuration from one WSUS server to another, but also includes a script to switch the modes of the server from replica to standalone mode. Mark also includes links to the WSUS Migrate tool and articles from other bloggers who have had the same challenges.
You can access his article here...