[H] media Center product key?

[Winterlight]

I just hooked up my SiliconDust HDHomeRun PRIME  HDHR3-CC. I had Cox 
authorize it, then started the Media Center setup and within a couple 
of clicks I see

Active support for digital Cable
To view and record premium or high definition TV channels you must 
enter a product key.
select Next to enter your product key.
I look on my Windows 7 DVD and input the product key but then Media 
Center says no..that's the activation key

what key are they referring too.. where do I find this key?