Using an IDE gives easy access to the Javadocs for the system (as well as the source code for the library if you are curious) and eliminates virtually all need for reference books. That said, a standard text editor plus the command line is basically all that is necessary to start.
I've been programming in Java for over 12 years, mostly Swing apps, and now use Netbeans, which I also use for C++ and Qt 4 programming. Its a very conventionally designed IDE. Most people I know find Eclipse bloated and confusing. What the heck is a "perspective" anyway? (I ask rhetorically.)
Recommended book: Thinking in Java by Bruce Eckel. Perfect for one with some C# or C++ experience but not good for programming beginners.