Of course I can only speak from my own personal experience, and some of the developers I talk to have different opinions...

I started out learning Action Script for Flash 5 then extended that to the browser environment with JavaScript. I figured I should learn some server side language and started to teach myself Perl and then added some SQL to talk to MySQL databases, but Perl was a beast for me to learn and I finally decided to bite the bullet and teach myself PHP also -- a decision I've never regretted. Of course I can also use CSS to great depth and (x)HTML or XML as needed.

Other people I know prefer Perl over PHP (but they haven't tried PHP either), or have learned ColdFusion as database middle ware.

So it would seem I support PHP, and I do. But it also really depends on what work environment you are going to be in. If you are an independent developer, sub-contractor, or freelancer then PHP may be just the ticket. If you are going to be working for an agency doing web development then you might want to consider ASP instead. I know squat about ASP except that my friend works in an international marketing agency and the "good money" there is either knowing ASP or being a Flash developer.

In short, PHP has a ton of functionality and can do anything I will ever set my hand to (which is quite a bit) and more, with a multitude of built-in functionality and extensions just waiting to tap into.

About javascript: It is wonderful, easy, and fun to use. I only use it for functionality that does not matter or will still be functional (if in a more-limited capacity) if the visitor has it turned off in their browser or if it's not available.

About Action Script: Flash is great -- don't listen to all the nay-sayers out there -- it can be light and fast and functional-navigable if you do it correctly (key point here). It also is in ~98% of browsers installed (after downloading the plugin) if you believe what the statistics say. The nice thing is that what you do in Flash will be darn close to the same on whatever browser displays it, something you can't say with HTML, CSS, or JavaScript. Plus it's big money if you become truly skilled in it and get your foot in the marketplace doing it.

Hope some of this helped,

langsor