NOD32 and Kaspersky has been my top 2 choices for AV for the past couple years. Light-weight, high performance, and easy installation.
I've been struggling with finding an AV for years that I was happy with. Tried Kaspersky many times in the past, but always found it to be a resource hog. I have heard the newer versions were supposed to be better, and AV comparitives listed Kaspersky as slowing the system down about as much as McAfee. So I got a 3-user license to Internet Security version at Fry's last week ($0 AR). That was a big mistake...
I have a Core I7 running at 3.6GHz with 8GB memory, Vista 64-bit. At first I didn't notice a problem running it for a day or two, but then I started doing some real work on my system and had to go running through folder after folder. I noticed about a 1/4 second+ delay each and every time I double clicked on a folder on my HD whether I had just been there or not. I thought it was just a weird memory issue so I rebooted... Still the delay... Okay, the only new thing on my system was Kaspersky, so I disabled all protection, firewalls, etc. Still the delay! Reboot with it disabled... Still the delay. Okay, I had had enough. Uninstall this hog, reboot, NO MORE DELAY.
Absurd. I fly through hundreds of folders when I'm doing web design or other projects and I can't stand to have some annoying and very noticeable delay with every click. I just cannot believe it still has the delay with protection disabled. Truly bad programming there.
I'm back on Avira free for now, but will probably buy the full license soon so I can have web protection.
As for Nod32, I had that several times in the past and it just could not detect trojans very well at all. Kaspersky and Avira usually found them, as did Malwarebytes, SpywareDoctor, and sometimes Adaware, but not Nod32. It is fast though.
For crying out loud