To install Java on Windows go to the following link:
and select the JDK(Java Development Kit). This will include the JRE(Java Runtime Environment).
You may need to add the following to your environment variable.
If you don't have it already you will need to download Java 6 from http://developer.apple.com/java/download/.
After installing Java you will need to set the following environment variables in your ~/.profile
Install Java 6: