Installing Office XP

I’m trying to install Office XP on a network for 300 computers. i’m sharing the cd from the server and i just create a username and a password and computers are already on domain. I can login fine and the OfficeXp setup starts with no problem but what i want to know is how to install without asking for the product key.. or is there anyway to make an autorun file so it can read the product key automatically. I want to know what file to edit.