[Java] Compile in Java 6 with NetBeans

Hello,

I have NetBeans 7.1.1 with JDK 1.7.0_04.
It compiles my project for Java 7 while I need it to work under Java 6 (or Java 5 if possible according to a Google search on the subject).
Can I choose to switch between Java 6 for some projects and Java 7 for others?
Or how can I make it compile for Java 6?

I am creating a Minecraft plugin (CraftBukkit), and it works very well on a server launched with Java 7, but does not work if launched with Java 6 (errors are displayed and thus the plugin is not launched).

I assume I need to install a lower version JDK, but I would still like to be able to choose between JDKs or know which file contains the information on which JDK to use for compilation.

PS: Since I will be reinstalling NetBeans on another computer this weekend, could I have the links to the JDK and the version of NetBeans to use?

Thank you for your help.