Best AV for netbooks

I've used AVG for a while and it was doing OK, and then I switched to AVG as I was told that it's lower in footprint, it seems that antivirus software always keep going up and down in terms of CPU and other resource usage, so you have to assess the AV market again in a few months to see which product is the most efficient.

Avast was OK, and I was told that it is by far the best system, however I found that when performing system scans Avast took too much resource and din't allow my netbook to function (n270 2Gb ram), on the other hand AVG seems to slow down my system a little bit more when it comes to day to day use (especially boot time), however their system scan was super efficient and I barely noticed it when it was running.

What's your AV policy towards netbooks?