While I'm sure you're probably familiar with much more regarding this area than I, I thought I'd suggest two digital distribution channels that Voxatron may do well in.
- Indievania.com is currently in Beta, but I'm extremely excited by it.  It's looking like it's going to turn into an awesome marketplace for indie games.
- GamersGate.com is a little more mainstream (they distribute retail games as well), so Voxatron may get buried/lost here.
One of the biggest advantages to an exterior system like this is that it would allow buyers to get updates much more reliably, and easily, as they wouldn't need to worry about losing their original email with the download link in it.
Actually, I left Steam out intentionally.  There have been numerous posts in the BBS about Voxatron breaking while trying to run through Steam; something about the overlay doesn't agree with it.