Thanks for the useful information,
How can I improve the system that will support ~60 servers? is it possible to improve Memory Bus?
I'm using a SAN, so Disk I/O will be better if I increase the amount of disk, right?
Is there a way to use this tool for free (VMware Capacity Planner)?
BTW: I forgot to mention that I have 2 servers (with the same configuration) which have the HA mechanism between them and a SAN.