From what I can tell, the Antivirus industry will be facing some major changes very soon.  Microsoft has introduced a free antivirus program called Microsoft Security Essentials.  Just click the link to visit the download web page.

In the past, I have often recommended  programs like Avast, or Eset's NOD32 over Norton Antivirus.    While I am still testing this new antivirus program on several computers, from what I can tell, it is a good program and does not noticeably impact the speed of the host computer.

I've stayed away from Norton Antivirus because it used to slow down my computer and cause all kinds of other problems. I've seen many customer's computers slowed down to a crawl because of Norton Antivirus.  However, I have heard that their new version of this program is a lot more light weight and faster.