Depends on what you want to do. For full blown programming I'd recommend C/C++ (I prefer the Java environment, but it's still a bit twitchy at times). If it's client-side admin's to PHP-based webpages, or a simple db interface (query, update, etc.) take a gander at PHP-GTK. A new, but maturing quickly, bind of PHP to the GTK Toolkit. Brings all the functionality of PHP together with the strength of GTK and gives almost complete cross-platform functionality. For client-side site admin's, most of your existing admin section routines are valid... you just need to write a nice pretty GUI through the GTK extension for them. More info on php-gtk can be found at:
http://gtk.php.net/
http://gtk.php-coder.net/
However, like I said above, it still doesn't compare to the raw power of C or Java...... though it beats VB as soundly as PHP beats ASP, IMHO🙂
Cheers,
Geoff A. Virgo