Good to see you've got it working. Just one small point - WSUS doesn't push anything - it's a completely "pull" technology. The server pulls updates from the MS web site and stores them. Clients then "pull" a list of updates from the WSUS server, check for what they need, pull those updates and then notify the server of what they've done.
Originally Posted by frognet1970
the point about sysprepping is a bit of a red herring; you do need to sysprep machines before imaging but that doesn't fix the WSUS ID (although there's nothing to stop you adding the commands that @fn-gm has posted to cmdlines.txt in sysprep so that it gets cleaned up)