If it's not showing in Auto Updates you may need to update the audio drivers for the PC or ensure that a few prerequisite updates are already installed; click here
No keycode for SP1...not sure what you mean. Go to start orb, type
press Return, the window that opens will tell you if SP1 is present.
Download the entire package; click here
If you install it without checking the audio drivers for compatibility first you could end up with time-consuming problems - it takes a fairly long time for the service pack to install and uninstall.