You will need to use the PC maker's restore process or install Windows from the original media, activate Windows, and then go to Windows update to get all critical security updates. Once that's done, install OneCare from the member center at
http://onecare.live.com, activate it with your subscription LiveID and then restore your data. Finally, reinstall and update your other software.
-steve
~ Microsoft MVP Windows Live ~ Windows Live OneCare| Live Mesh|MS Security Essentials Forums Moderator ~