it should be built-into sp2.
Sometimes, very rarely it doesn't get updated when you install SP2.
Go to Device Manager and Go to USB controllers.
There drop down that list and select one of the "Host Controllers". Right click and select "Update driver"
and select "Install the software automatically(recommended)".
It should get it updated this time.
And next to the host controller it should read as "Enhanced Host Controller"
Hope this helps