By chance on Sunday I discovered there's a new update to MPEG Video Wizard DVD (and two bug fixes are also for the non-DVD version). Incidentally, the auto-update feature of the previous version didn't seem to work, so you may have to go to the Womble site to get it.
At last it will allow multiple titlesets on a DVD, and the DVD menu editor has been revamped.
August 2008 Update Release
List of new features and bug fixes.
(NEW) DVD editor:
multiple video VTS export;
multiple audio stream export;
motion video menu background; and
more flexible menu design and template controls.
(BUG) minor bugs and feature enhancement to Timeline.
(BUG) minor bugs and feature enhancement to Export batch.