I would suggest learning gtk-perl as well. It may look intimidating, but I find that it's api is more intuitive and easier to use. Gtk has a number features that Tk doesn't, and you will probably find that you want to use them as your gui programs grow more complex. Gtk also has a more modern, polished look to it. I'm not trying to knock Tk, it is a powerful toolkit, but I find that Gtk is much more rewarding.