Reboot to clean preset environment

I was looking for help on how to setup a mac so that when the computer is rebooted, it will remove any changes that occurred in the last session.

I would like to setup a mac with a preconfigured layout and application list, and once the computer is rebooted, i would like for any files that were saved to the computer and changes to any software to revert to the previously configured layout.

Thank you for any help you can provide.

Mac OS X

10.5.8