Perl is freeware. You get the best results if you get the Perl source code and build it on your local machine. This may sound like a lot of work, but the configuration scripts that come with the source code make it easy to build and install. You can get the source code via anonymous ftp as follows:
Each of the machines providing the source code keeps things in a slightly different way, so the best strategy is to look for a README file and follow the local instructions. At the time of this writing, the most recent version of Perl was >5.0. We are currently running v5.004_04on surf.
For those of you who wish to know more about Perl, there are two excellent books [1], web sites containing on-line manuals (http://www.eleves.ens.fr:8080/cgi-bin/perl-man and http://www.cs.cmu.edu:8001/htbin/perl-man), and at least one user group (comp.lang.perl).