PC Pro and Which both ran articles about AVG and Symantec cheating users out of service. These two companies set the expiration date of your subscription based on when you renew. Every other vendor however, extends your subscription by the renewal duration. Meaning when you get the notice that your anti-virus expires in ninety days from AVG or Symantec, you’ll lose ninety days of service if you renew immediately.
AVG provides a decent anti-virus package, and their boot cd scanner has helped me clean more than one virus. Symantec however is generally regarded as snake-oil and should be avoided. Practices like these are why we recommend Avast! antivirus.