How do I enable VT-X?

I'd like to provide a guest OS with multiple CPUs in VirtualBox. My host machine is a quad core HP Compaq and uses the Intel Core 2 vPro hardware.

However, when I try to enable the setting in vbox, I get an error that VT-x is not available. Is this something that I can enable somewhere? how do I find out otherwise whether my hardware supports it?

edit: per suggestions below, I tried using the Securable tool, and it reports that hardware virtualization is "Locked Off". The processors are reported as "Intel Core 2 Quad CPU / Q9400 @ 2.66GHz"

You can use the tool Securable from Gibson Research to find out if your hardware supports virtualization extensions. If it tells you that your hardware is supported, but not enabled, check the BIOS settings to enable it.

Start your PC, press F2, go to the security option and enable VT technology.

Your processor does support VT-X, you'll just need to enable it in the BIOS settings. Reboot your computer and press the specified key on the boot screen to go into the BIOS Setup and enable it.

This may not be obvious. Its sometimes called vanderpool technology in the bios without mentioning virtualisation.

As a side note: some laptops require you to shut down and power off the laptop after enabling VT-x in the BIOS, and removing the power cable and battery for 30 seconds. I just today had such a laptop, and found this solution here.