I put 32Gig in my iMac, then ran ESXi as VMs under Fusion with demo licenses of vCenter. I used Microsoft's iSCSI target on a Windows VM for the storage initially, as well as a FreeNAS box for NFS ...
Every IT pro remembers the first time they built something that just worked. A perfectly tuned lab, clean deployment, the moment everything clicked. VMware certification gives you that feeling again ...