#1- get rid of Norton. Get Avast! at http://www.avast.com/eng/avast_4_home.html
#2- You couldn't have reinstalled Windows- if you did, all your information would be gone, including the virus. You may have repaired Windows, or did a System Restore, but I don't think you installed Windows.
#4 Download ad-aware SE, a free program to remove pop-ups (adware)
#5 Download Spybot- S&D, a free program to remove spyware.
NOTE: All programs listed here are freely available on the Internet. They are also free, and come highly recommended. Good luck....