I'm using an HP ProCurve 4204vl switch and our VMWare servers, our NAS and our workstations are all connected to it. I doubt though that this is the best way to do it ... shouldn't the traffic by the servers and the NAS be somewhat separated from the traffic by the workstations? Although, of course, all need to communicate with each other.
There are virtual servers on the NAS that run on the VMWare hosts: shouldn't they be connected somewhat more 'intimately' (VLANs?) ... ?
(the whole infrastructure is going to be upgraded though at some point soonish so that the VMs don't have to run on NAS anymore but on a SAN).