Well, here is the std Perl threads tutorial http://perldoc.perl.org/perlthrtut.html .
And more MS specific http://aspn.activestate.com/ASPN/docs/ActivePerl/5.8/lib/threads.html as you'll prob be using ActiveState Perl.

I've only ever used it on Linux & Solaris, but it works fine.
You just have to be careful, especially if you've never used threads before.
Note that if you want a multi-level variable eg HoH... to be thread shared, you have to explicitly share each level as it's created.
Something I learnt from BrowserUK.
Anyway, as usual, feel free to ask qns.
It's true that officially it's not prod ready as some (or more) modules are not guaranteed 'thread-safe'. However, there are many threaded perl progs running in production.

Cheers
Chris