Oh boy, you wanna start a flamewar? =)

Perl runs equally well on any flavour of Linux. And when it comes to choosing a Linux distribution, in the end, it comes down to personal choice. Distributions differ from each other MOSTLY in terms of where they put various files; different versions of the same distribution will have different libraries (which can cause problems with prepackaged binaries that expect different versions of those libraries) but for the most part, there's no one deal-breaker. Every version of Linux that I'm familiar with uses Perl a lot, so you'll have no problems finding Perl for whatever you end up using.

If you're new to Linux, I like to recommend (as a ladder you can kick away later) Redhat, if only because it's the one with the most info out there. Alternately, use Mandrake (highly RH-compatible in most respects, quite 'user friendly'). Note I make these recommendations only for while you're learning.

Once you get comfortable with whatever you start out with, you can explore other options (I use Debian a lot, and I like SuSE as well). Most Linux distributions are available for the cost of a download, or you can try various sites that will sell you a set of CDs for $2 or less (better yet: many of them offer multi-distribution packs that let you try out a number of distributions).

cheapbytes, LSL, and LinuxMall are all good places to start if you want to buy some CDs.

HTH

Philosophy can be made out of anything. Or less -- Jerry A. Fodor