This is my first post here, was just browsing the “unanswered” threads and felt like replying here.
All I have to offer is that if you are rendering for Architect for purposes of burning to DVD, the recommended method is to render video and audio separately. Video to an MPEG-2 NTSC Video Stream of some sort, and audio to AC3. This way Architect doesn’t have to re-render your project again and lose more quality.
Good luck!