Quote: "I'm also using Spybot for more in-depth scans. I recommend those two for your main anti-virus software needs."
Most AV software isn't quite up to date on malware yet, so I would agree something like spybot is useful and almost a must. But I don't think spybot runs passively in the background does it? A firewall can also help you detect issues by alerting you of outbound connections. Nearly everything you install attempts to look for an internet connection, even DB.
It's also hard to say which AV is really better. Sure Avira detected the most, but it also had one of the highest false positive counts in the tests. In the long run that may keep you safer, but it isn't the most accurate. I'm pretty satisfied running Symantec corporate. Task manager says it's currently using only 4.2MB, and I think that's pretty good. Even though the tests on the link I showed above tell me it's not the most effective AV available, but performance-wise it agrees.
Then again, who's to say that never getting a virus notification means your AV is good? Could mean you're full of infection and it just doesn't see it. It also comes down to the user's habits. You or I are less likely to pick up a virus or become infected from malware than our mothers.
Sorry, didn't mean to hijack the thread into an AV debate. Either disable mcafee or check it's settings to see if its performing a regularly scheduled scan.

"Any sufficiently advanced technology is indistinguishable from magic" ~ Arthur C. Clarke