I seems the Xeon E5540 ticks all the "fun" boxes for Hyper-V (especially VT-d) on Windows Server 2012. The only one conspicuously missing is "Trusted Execution".
I read the information on Wikipedia and Intel's page. If I understand it correctly it enables the OS to mark data as non-executable and prevent attacks in various ways.
So I understand it's generally a good thing to have. Question then becomes: If I use this CPU (or another CPU w/o Trusted Execution) in my Hyper-V servers, how am I potentially shooting myself in the foot? What features will I NOT be able to use?
Chips with the "Trusted Execution" basically allow EFI booting to work correctly and to make use of a TPM module. Since you're using Hyper-V, there's no purpose for this technology. Most Xeons that I've seen actually lack this feature in particular anyway.