Via HD Sports Guide, below is the coverage map for Saturday's Michigan-Michigan State game.

Those in the yellow will be able to watch the Michigan-Michigan State game on ABC. If you're in the blue or green, the game will be shown on ESPN. It isn't clear if it will be in HD or not on ESPN, but at the very least you will be able to watch it in SD.

UPDATE: Here is the HD/SD coverage map:

Basically, if you're out of the ABC region and are forced to watch the game on ESPN, you won't get it in HD, which kind of sucks.