My advice is to not invest into HD Satellite receivers and off-air antennae. Even if you are doing the installation yourself, the cost is considerable and not worth the investment in comparison to the amount of broadcasting that is currently available.
My advice is to wait until your Cable Company begins airing HD to it's viewers. My local cable company will be starting to air shortly and is in the process of making available a set-top box that will work alongside it's digital cable box. The cost will be $300.00 to purchase or $10.00 a month to rent. Since my television is HD ready, I will probably be looking to rent. The reason being that set-top convertors will get better and cheaper, and it's best not to committ so as to leave your options open for the better stuff that comes down the pike.
This will easily take the hassle out of setting things up the other way, and is far more cost effective and consistent from a reliability stand point as well.
It has been my experience as an ex-installer that omni-directional antennae usually suck. Go to Radio Shack and purchase only the UHF section of an off air antenna if you are bent on going the other way. Also, if there is a wife acceptance factor to take into consideration, try to install the thing in your attic. I've done this many times and often got good results. It doesn't always work however, so you may have to install on the exterior of your home.