I have bought one copy of Office 2010 Pro. How many computers can I install it on?
According to this page that interprets the Office EULA, a retail copy of Office can be installed on both a desktop and laptop for your own use.
I bought a Retail Copy of Office and installed it on my PC. Can I install it on my laptop, too?
Yes. You can install Office on your laptop as long as you are the exclusive user of the laptop. This means that you can install it on your laptop, but not your wife's laptop. It is important to understand that the EULA allows you to install the second copy of Office on a portable device like a laptop, not just some any other PC. In summary, you can install a retail copy on your desktop PC and your laptop. It does not mean that you can install it on two desktop PCs. You don't have the right to install it on two PCs. You have the right to install it on one desktop PC and one of your own laptops. Any other combination is not allowed.