How to install Ruby on Rails

For Ubuntu:
sudo apt-get install ruby ruby-dev postgres libpq-dev libopenssl-ruby
sudo gem install rake rails postgres ruby-debug-ide

To allow users to install gems:
chmod -R 777 /var/lib/gems/1.8

For Windows:
install ruby (using the one click installer!)
install postgres
gem install rake rails postgres-pr ruby-debug-ide

Points to note:
NetBeans 6.1 cvs doesn't work on windows - use 6.5 instead
Also, let NetBeans install the fast debugger (ruby-debug-ide)