If you're going to use a Prescott, be careful with the power supply of the motherboard. The Prescott demands a higher power supply.
Some mobo makers have produced newer versions/revisions of the same motherboard to take care of the power supply - I think it needs to be at least FMB 1.5 - so FMB 1.5 or FMB 2.0 will be OK. Usually this is not included in the motherboard specs, so make sure it actually says it supports Prescott. click here for Prescott supporting motherboard revisions (and double check with mobo website).
You may have checked that these models all support the Prescott. If so, for this high end sort of motherboard, I would go for the Asus.