I have an IBM x3400 with 32GB RAM, 413 GB SCSI RAID 5 array, on 15K RPM drives, Dual Xeon 1.86 with four cores each. The Array is divided into two one for ESXi and later ESX at 40 GB, and the rest is for VM storage.
I have VMWeare ESXi running. 2 VM's
One is a DC with 2 GB RAM, 40 GB HDD, 1 CPU...