In addition to sysprep, you need a disk imaging tool. I use Ghost, but there are others.
If you have to set up multiple computers on a regular basis, an image management tool is the way to go. Take the time to read the instructions for making a boot CD. Configure the software, put the boot CD in, then run sysprep and tell it to reboot. The system will boot from the image software's boot CD. Create the image from the boot CD, then use the boot CD to put the image on each of the remaining computers. When you boot the system, sysprep will kick in and ask you for the initial Windows data (user name, system name, option to add to a domain or workgroup). Since the image will have Office already installed, you won't have to specify the Office license number again.
If you don't want to go that way, look for the Office Resource Kit. It will tell you how to build a .MST file. This file will contain the settings for how you want Office installed (what applications, options, etc.) along with the serial number. You start the Office installation from a command prompt and specify the .MST file as a parameter.