Windows Server 2008 Enterprise R2.

I am shopping for a refurbished PowerEdge server that will support Windows Server 2008 Enterprise R2 and HYPER-V in particular.  Can anyone point me to a list of PowerEdge servers that support hyperthreading and Hyper-V?  Before I purchase a refurbished unit from EBay or elsewhere, I want to be certain that it supports Hyper-V.  From my searches on the topic I surmise that starting with the "9th generation" of servers, hyperthreading was supported by the processors.  However, I do not know what list of servers constitutes the 9th generation.  Any help will be appreciated.