I know it's too late for the Super Bowl, but here's some info for the future.
First, you can get HD for free via an antenna, and almost any mid-large type will work. I've had back luck with the Terk's, and great luck with RS antennas. They're cheap, easy to install, and have good range and reliability even in weather. My current one is hanging in my attic, out of sight, and I pick up about 9 HD stations alone in Minneappolis area.
Second, you will need a HD tuner of some kind. Either built into the TV itself, or if it's HD-ready, an external box of some sort. I'm using a HD Sat. box I had when I was with DirectTV. I have cable now, but I can still run the antenna feed through that box to convert the signal for my TV even without being a DirectTV member anymore.
In the end, you have to decide how much HD programming you want to watch. I get all my locals(NBC,ABC,CBS) along with Fox, WB, PBS, a childrens station(the kids love cartoons in wide format), and a couple of news and info networks all in HD. I just got done watching the big game, and without the antenna, I wouldn't have gotten it in HD. Even with the HD cable package I have, they only give you a couple of HD stations(ESPNHD, 1 Showtime, CBS, and HDTV with movies). Setting up is easy, the really tough call is where you get your converter.
