Larry O'Brien clued me into the fact that the new DevHawk theme didn't render correctly in FireFox. When I redid my theme, I tried to be good and use all div and span tags, but apparently building a three column layout with a dynamically sized middle column that works on IE and FireFox is beyond my CSS skills. So I went back to using tables. Maybe the folks at CSS Zen Garden would freak out, but the table works just fine.
Larry also pointed me to ActiveSWF, a server side COM component for generating dynamic flash movies. You munge up an XML file describing the movie, hand it to ActiveSWF and it does the rest. Sweet. Only thing missing is a .NET version (I realize I can interop to COM, but that's a pain to deploy).
Thanks Larry!