@Garuda, Over our way the Norton products, in various flavours of endpoint, were so notorious for stopping critical software from functioning, and corrupting installations, that we stopped using it. I must say, we had less trouble with actual viruses compared to the chaos caused by Norton/Symantec.
On the AntiVirus front, I'm been relatively pleased with Avira, not that it is fast or has low system impact, but because it simply worked. Bitdefender is also a solid product.