Virtualization Times

I have a virtualized vSphere 4 infrastructure (running in VMware Workstation 7 on native OS Windows 7 64-bit). Everything worked nicely until I wanted to add an Nexus1000v to the infrastructure (to a virtualized ESX4).

I can't add the Nexus 1000v OVF to the ESX. Error is "Host CPU is incompatible with the virtual machine's requirements at CPUID level 0x80000001 register 'edx'. ... Longmode; required when a virtual machine is configured for a 64-bit guest OS. Note that for system with Intel CPUs, enabling VT in the BIOS is requiredfor longmode support.

I assumed that this is due the 64-bit OS of the Nexus appliance, so I added an Windows 7 64-bit and got the exact same error message.

I already setted the ESX settings Processor preferred mode to "Intel VT-x or AMD-v", "Automatic" and "Intel VT-x/EPT or AMD-V/RVI", but nothing helped.

The physical hardware is a Dell Latitude D830 with Intel Core2 DUO CPU with 8 GB memory. I'm able to run the Nexus in VMware Workstation, but as said, not able to run it in the virtualized ESX.

Is anybody able to run an 64-bit machine in an virutalized ESX host? And how did they do it?