NetBeans is the Open Source IDE sponsored by Sun Microsystems. NetBeans is cross platform (Mac OS X, Windows, various Linux/Unix flavors), and includes editor, debugger, source code control, documentation, task management, and many other functions through an extensible plugin interface. Netbeans supports other languages such as Java and C/C++.
Installing Ruby on Rails via the Instant Rails distribution(which includes Ruby, Rails, Mongrel, MySQL, and Apache) for Windows XP (and Vista). Details how to hook everything up to work with the Netbeans IDE.
This is a lengthy review/overview of NetBeans and does a pretty thorough job of coverings it major (and many minor) features. While it compares some things to TextMate and Eclipse, the details aren’t quite all right for TextMate. Read this is you want to understand what NetBeans has to offer as an IDE (code editing, debugging, database support, etc.).