We are looking at replacing our current email system with Zimbra and are looking to virtualize (about 4000 users). We would be putting in 3 quad core servers each with 36GB specifically for Zimbra. Our SAN is a fiber channel SAN. We are looking to run Mail and Calendaring (no briefcase).

How many people have virtualized using VMWare? Does anyone have a similar setup? About how big can we expect for our database to become with ~4000 users?