For our small office currently running 3 ArchiCAD 9 stations under OS 10.4.2, we acquired 2 new Mac G5 1.8Ghz, 1.25GB RAM machines, one is a dual processor, the other a single.
Equipped with a RAID and an external backup, on a network connected through a 100base/T Ethernet switch, one of these machines will be our dedicated file / print serveur as well as the residence of our TeamWork files and centralized libraries.
The question is which one? Will the single processor suffice for a serveur?
ArchiCAD places very low demands on a server. Pretty much anything will do (even a Mac Mini if you're not using gigabit). The biggest bottleneck is the network. ArchiCAD can be slow loading libraries from the server and faster pipes help this.
Short answer: Use the single processor machine as the server and the dualie as the workstation.