Norton 2010 is actually not bad, and very trimmed down.

Still, ESET NOD32 is the one to beat, IMHO

According to me these three should make the top bracket

Kaspersky Lab performs real-time email scanning & automatic hourly updates; Rootkit and keylogger protection.

BitDefender 2008 has a user friendly interface that scans all existing files on your computer as well as all incoming and outgoing emails, IM transfers and all other network traffic.

The NOD32 anti-virus software by ESET provides real-time protection against worms, trojans, spyware, malware, phishing and hackers. Also the Nod32 control center gives you can access to tons of customization feature and different types of scans.

Regards

Aditya