My two cents:
Since you are familiar with C and C++, you could pick up php very quickly. Here's a quote for you:
"A significant portion of PHP's syntax, conditions, boolean functionality and loops have been copied from C, and as such, PHP is an amazingly simple language to pick up, especially for those already familiar with C and it's derivatives. "
http://marty.anstey.ca/programming/php/
It will run on most any OS and is open source.
The php community is enormous and the daniweb php forum is the most active forum under the web development category. Php is one of the best documented languages on the web, with it's own user manual at www.php.net .
It integrates with JavaScript perfectly for DHTML and AJAX. It can connect with just about any database you can find.