...or this:
As I understand it, your new PC came with a trial version of Office. At some point you will need to pay for it if you want to keep it.
Method 2: The post-activation method
This method lets you convert to the full retail perpetual license version by using the Activation Wizard expiration reminders. Use this method after you activate the trial version of the Office 2010 suite or program.
After you activate the trial version of a suite or program, you can convert to the full retail perpetual license version when the Activation Wizard expiration reminders appear. In the Activation Wizard expiration reminder, click Convert to start the conversion to the full retail perpetual license version.
You can also open the Activation Wizard expiration reminder when you are ready to convert by doing the following:
1.Start the trial version of the Office 2010 program.
2.Click the File tab.
3.Click Help, and then click Activate Office.
4.Go to Step 4: Active the product key.
If I have misunderstood (I have a track record with that) try
HERE, for the full guidance.