No it is not a HDTV setup, so I can not comment on the quality of the locals. However, in Chicago I do have a Sony HD200 w/ a DirecTV setup (50 inch HD Monitor), and the locals are not that bad, however, keep in mind that Chicago has a much larger subscriber base, so that these locals are not as heavily compressed, therefore making it hard to judge what they would look like in Wisconsin.
While the feed is the same and the HD box does little to improve the picture it does have the ability to up convert the signal to (1080i, 720p, 480p), which can often lead to a somewhat improved picture, but there is no real way to get ride of digital artifacts.
If you do go the DirecTV route, you might want to think about asking your cable company for a lifeline cable, so that you could get just your locals, or if you have an OTA antenna this would work as well, so that if you are not happy with the quality then it is possible to switch, just for the locals, and most HD boxes have tuners that are capable of handling all three (SAT/CBL/OTA).
Also, there is quite a buzz that DirecTV is going to carry east and west coast feeds of CBSHD, which would help somewhat.