There is no such thing as an "HDTV recieve"r.

Broadcast television is divided into two standards. The old NTSC (analog) standard, and the newer ATSC (digital) standard. HD programming is an optional feature of the ATSC standard. Not all digital signals are HD, but most now have some form of HD programming.

Most newer TVs should already have a ATSC/DTV tuner built in.

To answer your question, you DO need an ATSC tuner to pick up Buffalo channels.

But if you already have an HDTV, I doubt you need to buy any additional equipment. Just hook the coaxial cable to the rear of the TV, and pick DTV (instead of "Air") as the source. :)