Picking up on Iceberg's reply.....
Shaw Direct offers 2 dishes: the 60e and the 75e. They differ only in size, and not in their ability to tune HD (the numbers refer to the horizontal dimension of the dish in cm). The larger 75e is recommended as the signal strength diminishes based on your location. At your location, you might get by with the 60e, but you may experience some problems in stormy weather. Both the 60e and the 75e are capable of receiving both SD & HD.
You can optionally use 2 non-Shaw dishes such as the Patriot 85 cm dish, one dish pointed at each Shaw Direct satellite, each dish using a non-Shaw LNB such as a Pansat PT-5600. The advantage to this setup is that, unlike the Shaw dish, the parts are available in the US, and you will rarely have any rain fade. The down-side is the cost of the the 2 dishes along with the switch needed. Also, if you live in an area where there is a Homeowner Association, thay may not let you have 2 dishes.
A third option is to buy only one Patriot dish and point it at Anik F1R at 107.3. This would give you almost all your English Programming in SD. You could then add the second Patriot dish later (for Anik F2) when you choose to go to HD. At the present time, Anik F2 at 111.1 carries French programming and much (but not all) of the HD.
Whatever dish you choose, when you attempt to tune your non-HD receiver to an HD channel, the receiver will simply revert to the previous channel that was selected. Note that you will not see an HD broadcast in SD; your SD receiver cannot decode the HD signal.