Program in C/C++, it'll take you longer and you'll learn far more. With Perl you don't get to play with neat things like pointers and learn how to avoid buffer overflows. You also don't get to learn how to manage extremely large amounts of code because Perl can be written so compactly and efficiently. There is also far too much solidly tested, freely available, well packaged Perl code. What fun is it if you're not even writing all the code yourself? Perl's also too high level, you aren't forced to do the fun, educational low-level programming everyone dreams about. Perl people are also way too helpful, so you'll be tempted just to take the easy way and ask for help when you get stuck. So as you can see, C/C++ is the obvious choice. I wonder if anyone will take this seriously... Damn you and your non-default theme!

Oh, and as for the graphical interface (I refuse to say GUI), go with Qt from trolltech. The API rocks, the implementation rocks, the documentation really rocks, it's GPL'd for non-commercial products and if you want to go commercial you just have to buy a developer license. It's also used by many major companies (adobe just released a product using it) and by THE ABSOLUTE BEST unix desktop environment, KDE. And no, I don't work for Trolltech :).