I've had numerous direct emails asking what are the requirements for hardware when running Virtual Server 2005 R2 SP1 Beta 1. Just to make this clear - even on hardware which does not have virtualization assistance from the processor, it runs just fine. It just means that you won't see the performance improvements I spoke about last week.
If you do have hardware virtualization assistance, by default, hardware assistance is turned on (setting is on a per-VM basis). If you wish to turn that off, you can under the general properties page for VM configuration.