Avast is really bad as well…. I would suggest turning off it’s firewalls.
2 good programs to use are: AVG and Spyware Terminator.
BOTH are free.
Edit: free.grisoft.com is a spot to get AVG for free.
Edit edit: A message from one of my friends on this topic “Better yet spend 39 bucks for Kaspersky 6.0. They update viruses signatures once every hour and have over 300k virus definitions as opposed to others at 99k”
Edit edit edit (My first triple edit): If you happen to use zonealarm, GET RID OF IT.