First, I'd like to say whoever thinks there's no serious web development in Java simply doesn't know what they're talking about. Probably the same kind of person who believes Java is incredibly slow. This isn't 1998. Things have changed a lot.
Second, I actually came from a PHP background. I think PHP gets a bad rap because it's so easy to learn, so there's TONS of "developers" out there who never took the time to learn how to properly design and develop software with it. But it can be done. If you go this route, look into an MVC framework. Zend has some really cool stuff.
Finally, I would personally recommend sticking with Java. Like many here probably, I make my living with Java and so I'm most definitely biased. I work on a "real time" Java team at a major corporation, and we deal with anything that is real time and deals with Java. This obviously includes web development, which is my personal area of expertise. If you name it, we've developed with it. I've used many different frameworks, both server and client side.
For the server side, I think the best Java framework hands down is Spring. Its MVC module is a dream, and the framework itself is very well designed. The API is well documented. There's loads of resources too. It's really a developer's framework; made by developer for developers. The Spring guys really know what they're doing. For the view, I'd say stick with JSP. The newer versions have a lot of powerful features over their earlier incarnations, and you keep full control over the HTML. Learning how to debug JSF/RichFaces/ICEfaces/etc is a pain in the butt, especially if you're still learning web development with Java. Other good alternatives for view would be lightweight templating frameworks, like Freemarker or Velocity (which Spring has good integration with).