CS3 license on two computers

I often take work home from my office computer to work on my home computer. I have CS3 design standard on my office computer and need to install the same license on my home computer. I just bought a new home computer and after installing the same CS3 it won't allow me to activate it. It says that the software is already licensed to another computer (my work computer).

I was told (and have read from other users) that you can use the same license for two computers. How do I get this to work? Is there some sort of activation/deactivation process? If so, what a pain.