How to turn on Intel VT in MacBook Pro 2011 (MC721LL/A)? I used to turn on virtualization on my PC by turning it on from BIOS. But how I do it on MacBook Pro, as I am using WinXP on VMware Fusion 4.0, but its very slow, and both Windows XP and Mac OS starts lagging. 

Is there any way I can turn on virtualization for Mac so that the lagging stops? It's really driving me crazy.

[Note: it's a 2.0 GHz Intel Core i7 quad-core processor ("Sandy Bridge") with 6 MB shared L3 cache for excellent multitasking.]
It should be turned on automatically. If you go into the settings for the Windows XP virtual image, then click advanced, you'll see a field for Preferred virtualization engine. It should be set to "Automatic" by default, but if you want to force Intel VT, you can select one of those options.

If you're lagging, something else might be to blame. Does Console say anything and how much memory do you have installed?