I would recommend just getting Toast 6. It will encode any QuickTime video for you to DVD (mpeg-2). Just drag your MPEGs into the Video tab, select a low or high quality and burn. It automatically creates the menu and pagination for you. Way cool and easy.
Toast is my new favorite Quick and Dirty DVD creator. I do a lot of client demos on DVD and while iDVD and DVDSP are cool, they are overkill for just dropping a few thirty second TV spots for review to DVD. Yeah, it's ugly, no cool menus and such, but FAST. I have found the encoding quality to be just fine for general viewing.
If you need it to look better (menus, not video), I'd use iDVD.