Finally got it! i can still publish the video (audio included) from vegas as a DVD architect studio format and it works fine. I had to go through DVDA’s settings to find the burn options and change the type of audio file it uses to burn which was pre-set to ac3. I changed this to the other option avaliable (not sure now what it was) and then it would burn the DVD perfectly.
Problem seems to be my copy of DVDA does not support ac3 format even though it is only itself telling itself to use it for burning. Made a dvd now so quite happy.
Thanks for all the help and time people it did help. Made me start filing through all the settings hidden in weird places…