For those wondering:
The Indigo2s do run an Open source OS, NetBSD ("...of course it runs
NetBSD"), check it out here:
http://www.netbsd.org/Ports/sgimips/
Pretty good from what I have seen, I've never done the install, I like
my SGI's with IRIX, but I do plan to attempt this one sometime in the
future.
Later,
mbutler