Just give a try to Rails, in 5mins you can have a basic app working thanks to the scaffolding. And with all the user created scaffold generator, the application might even look good!
To the OP, if you want to do web dev for the rest of your life, please, help yourself and learn RoR. It force you to structure your code/site/idea, which PHP totaly ignore. Yes its harder, for the first 2-3 weeks then it gets much easier and faster.
Of course there are more webapp built with PHP and ASP, but as someone else pointed out so is Windows. The popularity of these langages is mostly caused by the fact that they are easy to setup and allow you to code right away, without any prior design work (data model wise).
Yes I am a PHP basher because I worked with it and know there are better alternatives. When I am telling you to look at other alternatives I do so in a friendly (but I admit, brutal) way because if you dont learn where the technology is heading, you will be screwed.
Just go on
http://www.rubyonrails.com/ and look at the moto. Which other framework is designed for programmer happiness? And the mac is the best dev platform for it, so enjoy!