Get Ulead Movie Factory. It works like a charm. You can put basically any type of video file on, and as long as it fits onto that 4.7gb dvd, it will work perfect. You can create menus and all that jazz on it too.
What you want to do is just few mouse clicks in DvdReMake. It will put together 2+ DVDs preserving original navigation and menus: http://www.dimadsoft.com/dvdremakepro/ht_merge_full.php
