Dell is posting VMmark results for their Poweredge servers
Dell has recently measured various configurations of two- and four-socket PowerEdge servers running VMware ESX Server 3 using a beta version of the VMmark benchmark. The graphs shows a 4-socket PowerEdge 6950 with dual-core AMD Opteron processors has 57% higher virtualization performance than a 2-socket PowerEdge 2950 with dual-core Intel Xeon series 5100 processors. The 2-socket PowerEdge 2900 with new quad-core Intel Xeon 5300 series processors shows 51% better performance. Equally impressive, all three 8-core servers were able to support the same number of heavily-loaded virtual machines.