Then you need to cop that I7 and something that supports a lot of ram...
Otherwise when you actually get to building esx host you going to have to make them so small resource wise as to not be able to support more than a VM or more...
And when you run virtualization inside of virtualization (vsphere inside of vmware workstation) you run into a lot of nested ram issues...
If you are talking about simulating a real corporate IT infrastructure you are going to need a minimum of 32GB of ram...
When I set up my lab to study for my VCP and VCAP I had...
2 AD servers
1 SQL server
1 Exchange server
2 Vsphere servers
All of that was in vmworkstation before I even started building ESX host and started building vm's inside of vsphere...which is inside of vmwareworkstation...
I5's were the top of the line cpu's then so I just put together two desktops that had I5's and supported 32 GB of ram a piece
After I built all the above in workstation I was able to build 6 or 7 esx host spread across two clusters...