I\'m new to Ruby on Rails and so far, I\'m having a lot of fun learning it. Coming from the .NET world, it\'s been quite a switch as my IDE (Visual Studio 2008) sort of hand
Just remember that the open source world is about choice, so there are tons of IDEs. A popular one is Eclipse that should include rails development as a plugin (and they are very simple to install). Netbeans also supports rails IIRC.
Maybe it is time to get down and dirty with basic component tools, and then find an IDE. I always find when starting a new language that it helps to understand the raw toolchain and how things work before automating.
Personally, unless it is Java development (convoluted in itself) I stay away from traditional IDES and use a modular solution of Vim/Gedit/Makefiles and other automations.
GEdit on Linux/Gnome is a great compromise. You have a basic text-editor with syntax highlighting and a terminal embedded. Then you can add in plugins for auto-completion and class browsing if you want that.
Good Luck