My two penny worth either AVG or Kaspersky, the are very similar and use the same scanning engine, I use kaspersy, I find the interface easier, but for cost the free version of AVG is the best AV available, but make sure if u just have AV that u use a good firewall as well. Again I use the Kaspersky Internet security suite which is AV firewall and spyware all in one, but for stand alone firewall then zone alarm is by far the best.
