I am looking to build a compute farm that consist of 75 VMs. those VMs will be running mostly on Windows 2003 Std. 2 vcpu. 2 GB RAm and 150GB HDD.

The customer has been very specific that the CPUs on those 75 Vms will all spike at the same time, and will take 80% of the CPU.(which I am a little skeptical about), but nevertheless, I am creating the VMs now for his testing, so I'd like to know if anybody has done any high performance computing like that before or if anybody has any idea what are the best practises in this case.

I am running ESX 3.5 U4 with 4 x opteron Quad core 2.9 GHz with 128 GB each, on NFS for Netapp 6070. the networking is currently going through a 2 GB trunked pipe, eventually going up to 10 Gb.

Thanks for any advices or ideas.