I upgraded to HD from my current account. HD is free for the first 4 months and then costs $9 something per household/month starting the 5th month. The basic receiver cost about $99, which does not include DVR or TiVO. Their HD DVR cost $200 something. I ordered two HD receivers and you have the option to pay it while on the phone, add it to your bill, or split the costs for 3 months. They also setup an appointment to install the new 5 LNB dish and recievers on the phone.
All local channels that broadcast in HD will be available, WDCA 20, ESPN HD, ESPN 2 HD, HBO HDTV, Showtime HDTV, TNT HD and more. The rep also said there should be anywhere from a total of 30 to 50 HD channels by the end of 2007, since government is mandating that all channels be ready to broadcast in HD soon. Nobody broadcasts in 1080p yet.
Any leased receivers that will be deactivated have to be sent back at DirecTV's expense. Also, there is a 2 year agreement of their service when getting the HD package.
If you have any questions, ask away. I might be able to answer some questions.