You will probably enjoy the class most if you use your own laptop. That way you can make your scripting/work environment just as you like it - and use it throughout.
If you are on a Mac, you will already have Perl installed, and will have access to the unix environment and tools through the Terminal. You do not need to download Perl, although you may want to familiarize yourself with the use of the cpan tool for installing modules.
If you are using Windows,
Download the free ActivePerl distribution of Perl: http://www.activestate.com/store/activeperl/download/
ActivePerl makes it very easy to download modules that we will be using throughout the course.
If you are in Windows, you'll also need to download cygwin: http://www.cygwin.com/ (select the default or minimal install, and under no circumstances should you install cygwin's Perl, as this could result in endless path confusion). Installation is a bit of a drag (choosing mirrors and options, etc.) but you'll be happy to have some of the unix command line utilities.
The last bit is finding a text editor for writing your Perl scripts. You will need something that can do syntax highlighting (coloring the text according to its role), and preferably also tidy up the indentation of your code. The good old favorites are (Emacs http://www.xemacs.org/ and Vi http://www.vim.org/). These both have a bit of a learning curve, so you may be interested in other editors:
For the Mac, there is a recommended free editing environment called TextWrangler (though there are countless others):
If you're on a PC, you may consider PerlExpress: http://www.perl-express.com/ (free) or for an $50 student license you can get ActiveState's integrated editor/debugger (that you can use with PHP, Ruby on Rails, Ajax, etc. as well as Perl) http://www.activestate.com/Products/komodo_ide/?_x=1 (works on windows/macs/linux)
Finally, you can use Eclipse with the Epic extension for an integrated development environment (these will be installed in the lab if you want to try them out).
But in short, you can use any text editor you like.
You can also opt to complete the assignments in Python. This is recommended only for those who are already familiar with Python, because in class we will be speaking in Perl. However, if you prefer Python and want to submit your assignments in Python, we can handle that.