If you still have Virtual Server running, I would definitely recommend that you first migrate to Windows Hyper-V 🙂

However for the rest of us living in the real world, there is a cool trick to check if virtualization is actually running for your virtual machine.

You need to see the value of the following performance counter on the host machine, not the guest:

Virtual ProcessorfVpProcessorInHvmMode

or also found as

Virtual ProcessorHVM-VP is in HVM Mode

You can read more how to enable Hardware Virtualization in Virtual PC and Virtual Server in this article.