We could make life a lot more attractive than the alternatives for our
beloved coot developers if we keep current with operating systems, so
that they could focus on new features rather than backward-
compatability that they can only test with the aid of time travel or
frequent trips to the Smithsonian.
For OS X, the 10.6 upgrade for intel is incredibly stable, 64-bit, and
US$30 (and doesn't require a previous OS, contrary to claims to the
contrary). For ppc, 10.5.8 is the final destination. (For anyone
using stuff I compile, these two options are all I can do at the
moment.)
For Linux, RH3 is older than my first-grader. You can upgrade, or
better yet, switch to Ubuntu, which is free and has great
internationalization support. I did this five or six years ago and
never looked back.
For Windows, I think 2000 might be stable now.