Antivirus/malware with least impact on ononline gaming

Hey i used to use Nortons anti virus which had a TERRIBLE impact on system performance. ( i heard some other alarming things about Norton as well).

I just recently built a gaming rig and i am wondering what software i should get that would have a very low impact on system performance but is still able to detect malware effectively.

I just purchased Mcafee and i am running that on my laptop but it doesn't seem that you can disable it very easily. It seems a bit like Norton but i heard it was much better. Not really sure what the impact of my systems performance will be.

Suggestions? Google turns up loads of results but not knowing much about firewalls/anti virus/trojan software it is hard for me to make a educated decision with the information.

I'm using Eset NOD32 Antivirus and it seems to be working good. I have it installed in my new computer and my old computer which I had for about 7 years and I dont get any lag from playing any games or running any other programs.
I can also run spybot search and destroy with nod32 with no problems.
I havent used it for over a year yet so I dont really know how effective it is.
So far it blocked almost every viruses that tried to attack my computer. There was only one time when a virus snuck through.
But I tried installing the antivirus on my sister's laptop and it got laggy.
If you go to the ESET official website, they have a graph on antiviruses system performances.