Microsoft's policy on VM's (Virtual Machines) is that as long as the host machine has a licensed copy of the Operating System, you are licensed to use it on as many VM's as you like on that host as long as they are the same OS that you have licensed on the host. You can't for example run Windows XP on the host and Windows Server 2003 on the VM's with only the host Windows XP license. These VM's can also communicate with each other via a private (closed) virtual network or can be configured to be visible to other physical PC's on the same network that the host machine is connected to. This is all covered by the MS VM usage licensing.

As far as Poser is concerned, I highly recommend that you make sure you are covered by legal licenses. It is possible to run more than one copy of the software on the same network however. If you deny Poser access to the network when the Windows firewall popup occurs then the various copies will not be able to see each other. I'm not suggesting this as a method to circumvent the licensing structure! I just don't know whether Poser 6 and Poser 7 will run together or whether an upgrade license entitles you to use both simultaneously. Again, use this information responsibly because you will be violating the E-Frontier licensing structure if you use multiple copies of Poser simultaneously with only a single license.

The way I see it though is that if you have say 2 copies of Poser 7 installed and open at the same time, one to change something in a scene and the second to render it once you have made the change and saved it then this is a bit of a grey area as far as the licensing is concerned. If however you ran both copies rendering 2 separate scenes simultaneously then you would most definately be in violation of your license.