If network rendering, I would render DV as the nature of mpeg2 could cause problems when it puts it back together after the render.

Rendering using 2 HDD on a rig helps a lot.

I have a 40G system drive, and a 120G SATA drive. my working folder is always the SATA drive. and Rendering the original from system drive to my SATA works great.

I don't know whether this will shorten rendering time, but I've rendered with Vegas to MPG2 using the DVD Architect template and audio to wav as separate operations, and found the end results top-notch. What really added rendering time in Vegas was use of DNR and Smart Smoother filters, which have to calculate across frames to render each frame. DVD Architect would make DVD really fast with the separate MPG and WAV files. Rendering to avi, which then has to be rerendered to MPG2 (I think) by DVD Architect before being mapped to dvd-readable files could result in poorer pic quality and longer rendering time in Architect.