You must render to 720×480 for NTSC, or 720×576 for PAL.
I like to render to a high-quality format such as Animation, Quicktime. Then I take that movie into Compressor to make an MPEG-2 movie, encoded using 2-pass Variable BitRate encoding (VBR). Then I import that file into DVD Studio Pro and author the DVD.
It’s the same for other apps:
1. render high-qual MOV or AVI from AE
2. compress in a compression app (compressor, squeeze)
3. import into authoring app (DVDsp, Encore DVD)