Movie doesn't retain aspect ratio when converting from MVK to AVI

Well as the title says I am trying to convert a movie file that is in .mvk to .avi. After I finish converting the file I run it and the aspect ratio seems to be retained when playing the file in WMP. But when I load it into DvD workshop and preview the movie it crams the movie into a 4:3 screen where the other episodes (that I downloaded as .avi files) properly display in letterbox. I have tried several times to convert the movie and have tried several different aspect settings but they don't seem to make any difference.

At this point I'm at a loss, the aspect ratio is fine if I play it off the hard drive but as soon as I try to put it on dvd it gets messed up. Is there a setting I need to use that instructs dvd workshop the keep the 16:9 or is it in the conversion process?. I use VirtualDubMod to convert the file and I use MVKtoolnix (MVKextractGUI) to extract the sub titles. I have even tried to use MVKextractGUI to separate the different movie parts rather then VirtualDubMod but I have always used it to reassemble the parts into one AVI. I have used this process before and never run into this problem. Still I would appreciate your input.

Thanks!

--XK