I was thinking of adding DirecTV to get NESN HD but it's a good thing I dug a little deeper. You have to live in the right zip code. I do not. 01867 in Reading MA (In-laws house) works for SD and HD but mine, 04624 in Corea Maine only gets me SD.
This link will show availability for SD and HD.
http://www.directv.com/DTVAPP/global/contentPageIF.jsp?assetId=P3000004
This link will show availability for SD and HD.
http://www.directv.com/DTVAPP/global/contentPageIF.jsp?assetId=P3000004