As long as you capture it in DV-AVI (the native format), the quality should be the same with both programs as all you’re doing is transferring digital data from the source tape(s) to your hard drive.
Once you get the footage into Vegas, then render it out in MPEG-2 and AC-3 formats for DVD authoring and creation.
If you have less than 70 minutes of video, I always use a custom MPEG-2 template set to a CBR of 8,000,000. Anything longer and I use a VBR with settings determined by the use of bitrate calculator. This has been discussed here numerous times so a search will reveal the proper techniques to use.
Use the default AC-3 template.
Render both to the same folder and give them the same name. That way, when you go into DVD Architect, load the video file and the audio will follow automatically.