Nod32 is not a problem on most computers. It is a very effective antivirus program when combined with a good firewall, and some top AntiSpyware support.
I use NOD32 and it is superb. It has a very low footprint compared to other AV programs like Norton and the latest version has a revamped interface that is very easy to use. I use it combined with the free Comodo Firewall, Spybot: S&D and AVG Anti-Spyware, and it provides an excellent security barrier against malware.