If your overclocking, get the Asus. That simple. The worst decision I ever made was getting the Ic7. Overclocked horribly, reads temps incorrectly, about as stable as a sky scraper in an earthquake. Not to mention there is the 255 FSB limit at 1:1 and the puny cooler on the MCH (NorthBridge). The Asus also has LAN. The 2.4C on the Asus will overclock better than the 2.6C on the Abit, not to mention the 2.4C has the best levels of FSB/mem divisors due to its 12x multiplier. If you get the Asus, consider adding a small quiet 40mm fan to the NB Hs.
EDIT: The Ic7 has all sorts of problems with low latencies, and I forgot to mention 2 important details:
One of the worst layouts I ever have worked with, only reedeeming factors are the DIMM/AGP clearance and to a lesser extent the ATX;
I am getting my 3rd one off of RMA.