Visual Basic only runs on Windows. That disqualifies it for my purposes. (In my house right now, we have several Linux distributions -- Red Hat, Gentoo, Mandrake, Debian, Slackware, a couple of versions of Mac OS X on laptops, at least one Solaris box, and at least one OpenBSD machine.) I think only one of these machines has *ever* had any version of Windows on it, and that's long gone.

I've also never worked with VB (VBScript yes, but I don't want to talk about that). I have used Perl to control Windows applications. That's reasonably easy and effective.

Finally, armed with Mastering Perl/Tk, I've maintained and extended a GUI application with Perl and Tk. It looked fairly good and ran well. Other good toolkits are wxPerl and Perl-QT. I'm not sure how well-maintained the Gtk-Perl bindings are at the moment, but there are other cross-platform options besides Tk.

To sum up, I know Perl, Perl runs on more platforms, Perl can work with COM and DCOM, and I've used Perl with Tk successfully.