I had a copy of McAfee (ver 8.0 ?) It was one of those that schools provide. I used it for awhile, low key and all that, but not too long ago, my computer started acting funny. Long story short, it was infected with something that McAfee never caught. AVG is not bad, but it's not good as some others out there.
I've seen nod32 and Kaspersky recommended a lot. I tried nod32, it was nice and low key, but ended up getting Kaspersky since I got it for $20 at a sale. Both of those programs seemed to be quite unobtrusive when I used them, I do recall Kaspersky a long time ago and I had hated it as well, it was too bloated. I think the newer version(s) are lot less so.
I would download the trials of those and try them on your machine for a bit to see how they fare. Wouldn't hurt.