An attic installation can work in an urban setting where there is lots of signal, but it may not work for you.
If you want to try the ANT751, I think they'll have one at your local Walmart. Give it a try in the attic, and on the roof, and see how it does. If it does not work, take it back. Note that the trees are bare this time of year, so if you are aiming through bare trees and get enough signal now, you may not get any signal in the spring. See "Trees and UHF" here
http://www.hdtvprimer.com/antennas/siting.html
For those stations, you don't need VHF, so a UHF array like the Antennas Direct DB4e, or the Antennacraft U2000 or U4000 would likely be better than the ANT751.
If you want to experiment with siting your antenna, the Eagle-Aspen is really cheap
http://www.amazon.com/Eagle-Aspen-EA.../dp/B000GIT002 and would give you some idea of what you'll need to get those stations.