If you really just want to jump in with both feet, I would suggest looking at ColdFusion from Adobe. The developer edition is free and runs on windows, os x and linux. The documentation is authoritative and extensive, there is a very active developer community and only a few books you might want to dig into. The definitive guide is a series of books that can be found on Amazon
The nice thing about ColdFusion is that you can use it as a stepping stone to other languages and remain productive along the way. You can even mix it together with Java since it is itself written in java. There are also lots of goodies built in that you would have to scour the web for or pay more for in other languages. Things like full text indexing, graphing, server monitoring, ajax based controls, flash/flex integration, asynch os calls, etc.
You even have the choice of building object oriented code or procedural code, although some people would not count that as a benefit. Those people rarely agree on which style should win, though.
Cheers!
