I have a 90 minute video that I rendered in Vegas as a DVD NTSC Architect Stream, and a seperate AC3 audio file.
I made a simple menu, with a still image for the backdrop, a 1 minute backgound sound (prerendered as AC3), and three "buttons", each pointing to different chapters in the movie.

I then went to Prepare DVD, and DVD-A said that all file formats were perfect, no video or audio conversions needed. So I hit the prepare button, and it took almost 1HR to prepare.

Doesn't this seem like a long time since all the files were pre-rendered in the right formats?

System:
Barton 2800+
Asus A7n8X Deluxe
1GB PC3200 Memory Dual Channel
XP SP1
Maxtor 160GB SATA
Aopen DRW4410 burner