I am a Norton believer.
On weaker machines though, the real-time protection stuff really is a killer.
Basically, from the 2004 version upwards, the whole application "suite" got heavy.
Switching to Kaspersky or McAfee is a good idea, but I am still skeptical of those free apps like NOD32, Avast and AVG.
Norton is getting real bloated. I don't think I'll re-new the year's subscription with them when the time comes this fall...