When I first bring in video to the workspace and timeline I always render the workspace. This gets me nice smooth playback during the editing process and I get the nice green line in the timeline. After editing the green line turns to red so do I need render the workspace again, get the green line before burning the DVD? Does rendering the workspace have any impact on DVD quality?
Pre-rendering has no effect on the quality of your final DVD.
However, the program can sometimes use your rendered files as part of the transcoding process, so pre-rendering can sometimes speed the process up a bit.
As Steve points out, the Rendering is basically for viewing. When one calculates the time to Render, prior to Export/Share vs any timesaving, the total times should be a wash, or very nearly so. The quality will not be any different.