Try this: Remove the VMware Bridge Protocol from the network adapter that you want dedicated to the physical host. Then remove all protocols, except the VMware Bridge Protocol, on the reamining two NICs. This will give your host one dedicated NIC to use, and the other two NICs can be used for the VMs.
Okay, I have generated some interest in this topic. But we would like to know if this could be tested.
Are you willing to test keeping the protocol bound to each adapter, but run the network editor manually (C:\Program Files\VMware\VMware Server\vmnetcfg.exe), disable automatic bridging, and specifically bridge to a single NIC that would let us know.
As far as I know, disabling automatic bridging in the GUI (vmnetcfg.exe) has the same affect as de-selecting the protocol from the NICs that you do not want to bridge to. (Although actually de-selecting the protocol at the NIC level will have a greater impact in that you won't be able to use custom bridging that that NIC any more.)
What we want to know is if this resolves your problem without manually undoing the vmware bridged protocol. If there is a functional difference, please explain how one method differs from the others. (i.e. GUI does not prevent duplicate ACK messages)
Please also see: http://communities.vmware.com/message/1080066/