Just let automatic updates take care of it if you have it enabled. I have done my laptop and gaming PC and all went OK apart from a slight sound problem, here is Microsofts warning as this update sorts out some hardware vs vista compatibility.
In order to install Windows Vista SP2, you'll need to have Service Pack 1 installed. Microsoft indicates that it might take an hour or more to install the update,and after you're done some hardware (like your sound card) might not work until you install updated drivers.