Hip remember this DVD Audio is not a commonly burned topic. Really you are not going to find a free program for burning DVD Audios. Burning Audio DVD's is not the same as burning a music CD's Believe me I was looking for this same thing a while back only for Linux and I pretty much got no where.
Really what you need to do this task is use a program called Vegas Video Pro 9 From sony Creative in conjunction with DVD Architect pro. The only issue with this is the software is not cheap at all. although you might be able to do this with a simple DVD mastering software and treat it like a DVD Video. I know the Audio DVD's that I have do have some type of Video to go with the Music (still Pictures for each track) But burning Audio DVD's is an expensive task
Yeah its tough...its hard to find in ISO format sadly otherwise its a non issue.