While Microsoft is very firm on the "OEM license is tied explicitly to the original piece of hardware it was originally bundled with" statement, VMware is a lot more vague.
Cisco VMware ISV1 support contracts (Cisco is one-stop shop, where you call Cisco to request Vmware support help) are definitely tied to only Cisco equipment.
I think the real issue would be when you try to call in for support. Doubt you will get very far calling HP for HP OEM VMware licenses running on Cisco Servers, or calling Cisco for help on ESXi issues running on HP servers with Cisco OEM vmware license ;) (Should note that Cisco TAC would probably answer some basic L0 questions regardless, and then point you on to your actual hardware vendor)
It's also helpful to remember that a VMware license and VMware support are 2 different things, and will generally be two different line items on an order. Buying a "license' does not get you support.
Buying a support contract does.
Thanks,
Kirk...
