You can certainly render an MPEG-2 video [I]with[/I] audio. As mentioned above, it depends on what render template you select, as to whether or not the output file will include audio. On any MPEG template, you can click "Customize Template", then in the pop-up window select the "Audio" tab, and tick the "Include Audio Stream" box.

The "DVD Architect Video Stream" templates do not include audio by default (but you can change that) because the audio format rendered inside an MPEG2 video file is a lower quality than the best quality you can use for a DVD.

It would be like making a music CD by starting with a high quality WAV file, rendering to MP3, then converting back to WAV (PCM) to burn the CD.

The normal approach for making a DVD would be to render just the video to MPEG2, render just the audio to WAV, then send both files to DVD Architect for creating the DVD.

However, having said all of that, it depends on how high the original quality of your audio is. If it is just casual audio from a camcorder mic, you might not notice the difference of the intermediate "lower quality" step.

In your case, your MPEG2 source video already has the compressed audio embedded in it, so you have nothing to gain by rendering the video and audio separately. Just tick the box to "Include Audio Stream" and you should be good to go. Alternatively, I think the "Program Stream" templates would give you what you are looking for.