I wouldn't OC a Xeon. They are meant to be stable at their clock speed. OCing ruins stability. Workstations aren't meant to be OCed. Why do you think the 3.0+ Ghz models are like 2k+? I'd just get a board for ~ $400 and run them at normal speed.
This is not going to be a server. In case you didn't notice Mark's sig he has all his systems OCed & stable with Folding@Home 24/7.