You can use these two methods to active your Microsoft Office 2010

How to active Microsoft Office 2010 programs
The following information is provided to help you to activate your Microsoft Office 2010 programs. If you are using the computer at work or as part of an organization, you might be using a volume edition of Microsoft Office 2010. I will list some information about how to active Microsoft Office 2010 programs.
When you enter your valid Product Key, the Activation Wizard automatically runs and it gives you two choices on how to proceed:
The one is activate by using the Internet ,the Activation Wizard automatically contacts the Microsoft licensing servers through your Internet connection. If you are using a valid Product Key that has not already been used for the allowed number of installations, your product is activated immediately. And when you activate through the Internet, your product ID (derived from the installation Product Key) is sent to Microsoft. A response (the confirmation ID) is sent back to your computer to activate your product. If you choose to activate your product through the Internet and you are not already connected, the wizard alerts you that there is no connection.
The other one is Activate by using the telephone. You can telephone an Activation Center and activate your product with the help of a customer service representative. When you use telephone to active the Microsoft Office 2010 programs, you should be aside your computer when you call, and you should have your software Product Key available. And it may take a long time than active through the Internet. The telephone number I haven't list in this computer because there are many numbers available and the telephone numbers vary by product license and country/region.
You can use these two methods to active your Microsoft Office 2010 programs when you buy it. And I think the first one is more convenient.