There is no licencing issues with ASP. It's free also, and if you are running almost any version of Windows since Windows 98, you've got a built in web server that supports it without having to install anything else.
Personally, I wouldn't recommend ASP to anyone anymore, as ASP.NET is so much better, and also free. Microsoft Visual Studio Web Edition is the free version of the development environment for ASP.NET (which by the way, you can use any language with - including PHP if you so choose), and there's tons of help and support freely available - although not as much as there is for ASP and PHP.
PHP is in no way more flexible than ASP or ASP.Net - I don't know where anyone would get that idea to be honest? You can achieve the same things with both languages, but ASP.NET is by far the most flexible and powerful.
Yes, it will take time to learn and understand the advanced features. But for the every day stuff, including data manipulation and integration, and AJAX support, etc... you can do it all visually without writing any code at all, although much better functionality with just a little bit of code - a few lines.
Clearly I'm passionate about this subject, but what I'm saying is true.
Check out
www.asp.net though - it's a superb resource.