Thanks so much Grant! I discovered that even though I was running Live Update, it wasn't saving the virus definitions and when running scans it was pulling from very outdated definition files. I did try the add/remove programs in XP, and removed what I thought was everything from my computer. I then downloaded NAV 2009 (I can no longer purchase the Corporate Editions through school) and tried to install but it told me it couldn't because it still detected other Norton programs. NAV then told me to download the Norton Removal Tool, but it was failing because it couldn't remove the Corporate Edition.
Long story short - I am trying to manually remove SAV, then remove NAV, then re-install NAV. Does that change what I should do?