When using PortID-based policy you won't see the traffic from a single VM balanced across both pnics. With this policy, whatever the first pnic the VM traffic hits it will bind to and always use that pnic until communication with that pnic ends (dropped connection, failure, etc). Then the VM will use the other pnic. As you have said PortID policy is really just round-robin.
When you have more than one VM, each VM will bind to either one of the pnics. VM1 to pnic1, VM2 to pnic2, VM3 to pnic1, etc. I don't think the logic is that exact, but you get the point. So in that regard you get some form of balance.
The kind of balance you're looking for will be via the IP-hash policy. HOWEVER, you might not be able to use this policy if your Nortels are connected to a higher level switch. IP-Hash requires an etherchannel which I don't believe you'll be able to enable if your Nortels connected to another switch. You should check with your network guys and test this before implementing in production!
I have HS20 blades with cisco switches in the chassis uplink'd to a Cisco 6513. I can only use trunk ports and PortID policy across the nics. Same problem.
