If you have not yet found a suitable application to convert your Xvid’s to DVD, give FAVC (freeware) a try. http://www.videohelp.com/tools/FAVC
It allows you to place I believe 8 titles onto a DVD with Menu’s. Great piece of software which is very easy to use step-by-step.
Use HC Encoder as your encoder (bundled in the installation) and you cannot go wrong. I have yet to encounter audio/video which is out-of-sync using it.
Requires Microsoft’s .NET framework v2 and at least v2.57 of Avisynth.
Here’s a guide: http://www.digital-digest.com/articles/FAVC_Video_to_DVD_Guide_page1.html