While Perl works on Windows, and GTK+ works on Windows, getting Perl and GTK+ to work on Windows is quite hard. I was searching for information on it a few days ago and everything I found indicated that no one had gotten it to work yet. Most of the messages I found were more than a year old, though, so things might be better now.

If you want to use GTK+, the best solution might be to suck it in and use C for the GUI and Perl for the backend.