are you running any java based apps like azureus?

If yes, then try adding exclusions into amon. Exclude all javaw.exe and java.exe files. There are a few copies of this file in java folder. Add all and you should see less CPU usage.

nod32 is a paid software. I am not sure which version you guys tested but my version of nod32 is paid and it works fine.

In fact, it's much better than norton/symantec AV. And most other free AV. It can detect a little bit of common worms which cannot be detected by pure av software like nav or avg free.

So, if you only have antivirus to install on your PC, nod32 is a good choice. So is antivir by avira which is getting quite good as it can detect lots of worms. But both is different cause one is paid and the other is free.