By no means have I done an exhaustive check of all the anti-malware companies yet, but it looks like virtual machine licensing is going to be a major differentiator between various products as we move toward the release of all the 2010 software suites.

Today, Sunbelt Software touted via its blog that Sunbelt's licensing applies per computer, not per instance.

"Our company policy is a single-user license applies to one box, and any VM sessions on that box. A single-user license is set up to allow multiple installations on one box with W7 and XP mode both running."

This becomes a pretty important distinction once Windows 7 and XP Mode come into play for those running Win 7 Ultimate, Professional or Enterprise (or any other hypervisor for that matter). Personally, I quickly found that a migration from Vista32 to Win7 x64 necessitated that I run a VM only for my legacy Cisco VPN client, which won't work on 64-bit machines.

Unfortunately, not every security suite is going to license VMs in the same manner. I'm currently testing one product (I can't say which due to an embargo), and I just learned that protecting the host and the client will count as two licenses.

So, as you evaluate what security to put on your new Windows 7 PC come October, remember to weigh how much security is going to cost you, if you need to spin up an instance to support some legacy application.