I've been told I'm biased on this subject but:

Learning how to write portable code is learning better perl, so this is an opportunity, not problem, if you decide to stick with Win2k. If you want to have a easier time at "using" perl, I'll venture that most target systems are Unix based so it'll be easier to use a unix based computer.

It is my experience that dual boot only works if you have a strong need for both OS'es, otherwise it's a waste of space. You're probably better of with linux and wine/crossover or MS windows 2k and cygwin.

extra: my ADSL connection works on PPPoE and I had very little trouble making it work on my linux machines.

Tiago