PCWorld enlisted the aid of AV-Test.org to evaluate 13 security suites and Norton placed above all others.
Battle of the Security Superpowers Article
Symantec Norton Internet Security 2011 Review
By the way, for those who may remember the challenge from Comodo for a head-to-head competition, both Norton and Comodo were included in this test:
Comodo Internet Security 2011 Complete Review