I'm using it because the Zektor Vector Generator is currently supported only in DOS, and my setup is a vectormame. Dmame now has ZVG support built in, so I can update along with everybody else. Of course, I can still only play about 35 games... Even if I were running standard mame, I think I would still use DOS, because now I'm confortable with it and I think its faster. Getting that PCI soundcard working was no fun, though.