I pushed for 3Ghz this morning. 4x250. The RAM speeds were auto set to 166mhz, and I turned down Asus's Memory Acceleration Mode. It booted into windows just fine, completed a few Sandra benchmarks, and took 15minutes of two instances of Prime95 and Seti@home all running at the same time.
Edit - But Asus PC Probe still gives a full load temp of 44^C, after running Seti and Prime95 for 30mins. The Real Time Clocker monitor reveals that the clock freq is holding steady at 3Ghz.