It's mainly your atmosphere - go into the atmo editor and choose Global Illumination and you'll be amazed at the difference. If you don't use that (or radiosity), then all your renders will have a kind of "pastel" look to them - no rich color to speak of. Your shadows won't be dark and rich (or go to black at ALL since every texture has 40% ambient - this info is used to calculate what is needed for GI and GR), your highlights won't "pop" - just kinda drab.

And sad to say, Vue still has noticeable grain in Broadcast quality. They count on the video signal itself to cover the noise - which it might over transmission, but not a DVD. You're going to have to up the quality to Superior if you want to really get rid of the grain in subtle shadows.

And lastly, yes, don't use any compressed format for your original render - try TARGA or TIF sequence as suggested above (I'm guilty of going straight to AVI myself, but for what I'm doing it works just fine) for the highest quality starting point.

Good luck!
-Lew ;-)