4.6.603 seems to do a good job, I don't have any viruses. I also have McAfee vs 9, it's turned off. I've ran the McAfee manual scan a few times with Avast! shut off, it didn't find anything. I'm testing Avast! for a replacement for McAfee.
No contest! Mcafee is the most complex, ineffective, destructive and above all interfering piece of "software" I have ever had the misfortune to come across.
The whole thing is eye-candy - from the pointless "security index" graphs on the main page to the feature that tracks where an "attack" is coming from. It's bloated, goes wrong on most installations I've seen and doesn't actually detect as many viruses as Avast in my experience. Most of my customers who use McAfee have actually complained about it to me and paid me to remove it, and after replacing it with Avast, have never had a problem!
As an experiment, try going to smileycentral.com and clicking the blue circle to "get free smileys" -- see which AV tool actually blocks the malware present in there.