Honestly they are both as bad as each other.
In 75% of cases of people I know that use XP and Norton they have had nothing but troubles.
Also I wouldn't trust AOL to get anything right.
You'd be better off going for any number of Anti Virus solutions widely available.
While you're at it don't forget to ensure you have some Anti Spyware as well.
To make sure everything is running fine run both anti virus and anti spyware apps in normal AND safe modes. (make sure that they are updated first !

) (
AVG is good and free AV)
(A couple of good removal tools are
Spybot and
Adaware)
ALso an on line virus and spyware scanner is
Trend Housecall
Just a note; actively running two AV's on one machine can cause problems.