Execute Disable Bit in bios is supposed to protect from some hardware server leval virus's. not sure if it would affect what you have.
 
Execute Disable Bit allows the processor to classify areas in memory by where application code can execute and where it cannot. When a malicious worm attempts to insert code in the buffer, the processor disables code execution, preventing damage and worm propagation.

How did you detect it?

There are many Virtualization techs that do not require VT CPUS
If you look at linux/mac projects there are many types, the thing is that some ass use thath tech to make virus.
M$ have many holes, adobe too, a remote execution bug will allow code inyection, from what I read they can virtualize whit only 600k injected on the bios. 
early example
http://en.wikipedia.org/wiki/Blue_Pill_(malware)
Fisrt thing your PC uses a simulated efi to boot...., all your Windows installations use fake components, fake drivers (all signed, they hack that too). 
  
a must read (root kit in acpi/ pic card)
http://www.blackhat.com/presentations/bh-dc-07/Heasman/Paper/bh-dc-07-Heasman-WP.pdf
 
the use acpi becouse of the irq and that IRQ in Windows work as SYSTEM so they own you, a look at your IRQ tables and hardware will show it: look for fake hardware Fireware/usb disable in bios and they remain in device manager the use extrange irq etc.
 
My first symtom was red dots at post, so I change my vga but they show another video problems thats when my search for bad hardware starts, and find fake hardware etc.
I have anothe machine HP hdx18 whit the same virus.
From my research they use cpu bugs too, thay have many ways to get in.
 
 
read your installation logs,windows and av logs, check the i/o read of your AV when you scan (they dont move much after 15000 files...)
 
this is not a paranoid or rooky post.