Always reboot after adding or removing a programme.
I'm a little confused by your post but I think that you are saying that remnants of SA are showing although you removed it...am I right?
Make sure that there is no remaining entry in Add or Remove Programs. (Programs/Uninstall a Program in Vista).
It could be listed as McAfee Security Center if you ever had other McAfee components installed.
I would try a clean up. If you have no other McAfee components that you wish to keep run the "MCPR Removal Tool" listed in my signature.
Reboot and then re-download it if you wish to from http://www.siteadvisor.com/
I can't tell you why the discrepancy in sizes and sacore is merely one component of SiteAdvisor.