old post but hopefully useful to someone.
I have setup Linux Clearos with vmware server 2.
Hardware is very light dual core with 8gb ram.
I have about 5 VMs running, Email, firewall, application server, ftp server,
linux based erp demo etc.
ESXi would be nice but hardware requirements are too much.
what i did was setup a bare minimum Linux install (ClearOS host) with
VMware server 2.02. works really great, Its been running 24/7 for almost a year.