I like Linux, because it gives me much better control over what's going on in my machine. Also, it provides an enormous array of programming tools, including the gcc compiler and front ends for all kinds of languages.

Even if you're not going to program in C or anything other than Perl, you might find yourself wanting a module that uses C and needs to be compiled. You can't always rely on the ActiveState version of Perl to contain everything you want. You'd need a compiler, and they can be expensive.

I would agree with other posters, though, that it's possible to get distracted with learning a whole new OS while you're also working on learning Perl. If this is a consideration (that is, if you actually have to *do* something with your computer), then using a familiar OS might be more reasonable.