There's also a port of NetBSD to the Dreamcast, although I can't imagine it's much more useful than the Linux port. Neither is really any good unless you have it networked to a host computer that can serve up some hard drive space. The Windows CE that runs on the Dreamcast doesn't really have a GUI at all, it's basically just the kernel that was sometimes used by programmers who decided it was cheaper or easier or whatever.

From what I've heard, the Dreamcast BBA has a custom chip inside it, and I wouldn't be surprised if the modem has a similar thing in it... I can't imagine any situation where it would be useful to adapt a DC modem to work in a computer anyways, especially since regular modems are cheap as free.

--Zero