There is one more HD option: Bell ExpressVu, the Canadian equivalent of Dish Network. It is the only way to get the 5 major U.S. networks now. They also just added Discovery HD and the Canadian equivalent of ESPNHD.
(I happen to have an ExpressVu 6000 tuner for sale but I promise that is not why I added this to the list of options that are being discussed
If anyone wants any info about Expressvu, let me know either in this thread or by private message.