Another server-side "scripting" language that's going to really take off soon in Java Server Pages, an ASP type clone using Java. The JSP compile on the fly into Java Servlets, and can tie into all the cool stuff Java does. (http://java.sun.com)

But it's very hard finding a reasonably priced ISP (30/mo or less) that supports it right now, since it's so new. Believe me, I've looked. But Apache is working on a JSP/Servlet bolt-on to their webserver, so I expect that to change within 6 months.

So.. PHP or ASP? I would recommend ASP if you are wanting to get a job doing web development. Lots of corporate webservers use Microsoft (especially in their intranets) and ASP is a given there. Also, you have the opportunity to grow into COM objects, offering better performance for large websites and complex tasks. There are a couple free hosting sites with ASP (but not COM objects) www.webhostme.com is I believe one of them.

If you're looking for a free/cheap way to add some server-side capability, then PHP is certainly an option. It may grow into a more robust professional tool, but currently it's ASP for the Microsoft types, and CGI/Java for the Non/Anti-Microsoft types that are for the big sites with millions of hits.