Is there any way to get Hyper-V to start in Windows 2008 on a PowerEdge 2800?

I keep getting a message saying that the hardware-assisted virtualization should be enabled in the BIOS.  Now, this PowerEdge has 2 Xion processors, and the Intel Xion does support virtualization, but I cannot find the flag anywhere in the BIOS.  I've upgraded the BIOS to the latest version (A07), still without success...

The Dell Support site does report "Windows 2008 x64" as a supported OS for the PowerEdge 2800, so I hope I'm just missing something easy somewhere!

Thanks,