This is just a broad brush...
To get started watching "free" OTA Digital TV on an HD-Ready television set, the Samson SIR 180 unit, about $600 now, will "decode" Over-the-Air signals from local commercial and PBS stations.
If down the road, you will decide on Satellite, then that settop box can be purchased to include an OTA feature and you wud not need the Samson unit.
To see what DTV signals currently are available in Milwaukee, go to www.antennaweb.org
This also will suggest a type of roof or attic antenna you will need, wired with RP-6 coax down to the settop box.
To see DTV channel programming, sign into (free) www.titantv.com
I dont have the quick link to what's programmed in actual High Definition HDTV but be aware that only a few are broadcast among the DTV fare.
Satellite will gain you some HD HBO, Showtime and HDNet tho not all on the same dish.
Also start reading THIS FORUM beginning with the FAQ.
the OTA only Samsung 150 lists for $599, but is discounted to approx $500 and also has a $100 mail in mfr's rebate, final cost approx $400. i've also heard of open box units heavily discounted at Best Buy, these are also eligable for the rebate.
three new Samsung models are sched for release in June, including an OTA only unit that will list for $399. after they become readily available, i would expect them to street around $325, maybe less.
HD over cable uses a different modulation scheme than OTA, you will need to use an HD cable box supplied by your cable provider. keep in mind that "digital cable" is not HDTV or even standard definition DTV. digital cable simply takes the analog tv signal, digitizes it for transmission over the cable and re-converts it to analog for your tv.