It is true that there are cgi forums, these are usually done in perl though. I believe i've seen some .asp forums aswell. But i'm not positive, i'm not that familiar with asp though i've been told its a good language to learn for those familiar with visual basic. When i find some free time, outside of work and learning how to use 3d studios max i may take a look at it.
Anyway, when it comes down to it. PHP is by far the best, the flexibility of it, and compatibility when it comes to servers and whatnot, and from my experiance, i'd say PHP.