I just got off the phone with Directv and I was told I can receive MSG in HD on channel 621, but that I need to get the new equipment and they will swap out my old for the new at no cost. They say the new equipment can transmit both signals, SD & HD, over one channel so that's why it's on 621. The downside is that they're in short supply of the new equipment and that could take 3-4 weeks. If you need the new equipment you have to join the priority list at
http://www.directv.com/hddvr If you have the new equipment and checked that your zip can recevie MSG HD then call Directv. They said they have some issues with customers not receiving it, might just be setting a switch.