i just went through replacing norton internet security 2003 with 2005, it gave me a slight headache when it froze during install, then i remembered that norton likes to retain its folders, so i did a system restore on xp, norton was corrupted (ie 2003 should have been installed because system restore was used) but i removed it from add/remove and left the folders there after it completely removed itself automatically....
norton internet security 2005 decided it wanted to install....
so in short, i suggest fresh installs.