With the great help of my co-worker, we installed a Channel Master 3016 (thank you for your advice, Bruce!) antenna in the attic. Mounted it using RadioShack Attic Mount 15-882. Then we spent about 2 hrs rotating it in order to get a decent signal.
At the end of the 1st hour we realized that we were getting a reflected signal instead of the real one (damn, hate the errors on antennaweb.org

) because no matter what, we could only get either CBS or FOX, but never both

By the way, it looks like WACH uses 2 different towers for the analog and digital broadcasts - analog picture is totally unwatchable, but digital gives a strong signal. If we turned the antenna to get the best analog on WACH, digital would disappear altogether.
Anyways, here are the results:
WOLO-DT on channels 25-1 and 25-2 - 100%
WLTX-DT on channels 19-1 and 19-2 - 77%-83%
WRLK-DT on channels 32-3, 35-1, and 35-2 - 77%
WIS-DT on channels 41-1 and 41-2 - 68%
WACH-DT on channel 57-1 - 63%
Still have 2 questions:
1. Has anybody noticed how bad WIS-DT on 41-2 was last night? The picture was very blocky (not breaking up though). Same type of picture you would get viewing a .MPG file with a very high compression. 41-1 was OK.
2. Should I get an UHF antenna amplifier? Would it improve the strength of the digital signal?
PS: NASCAR racing in HD last night on FOX was awesome!
Thank you everybody for your great help!
Kirill