McAfee anti virus is sort of a virus by itself on your computer in the way that it is so hard to remove it even if you have administrative privillages.
It is sad that McAfee took all their expertise and knowledge in virus stubbornness in uninstalling and implemented the same techniques to make uninstalling their own product so hard.
If you can't remove McAfee using Add/Remove in windows, just download this tool:
close all your apps, run it, and then use Add/Remove to clean up any McAfee products on your system.
If it is still stuck there or site advisor is not removed after removing everything, try running the following command line:
C:\Program Files (x86)\McAfee\Common Framework>FrmInst.exe -forceuninstall