I used to install the Norton stuff on my customers' computers. Good stuff if they keep it updated. Problems is, people are cheap and don't spend the 20-40 bucks a year to buy an annual contract, new disk, etc.
So I have found 2 free ones that work well.
Antivirus
www.avast.com
download it here
http://www.avast.com/eng/avast_4_home.html
Addware/Spyware
Lavasoft Ad Aware SE Personal
download it here
http://www.lavasoftusa.com/
Again, both are free and do automatic updates which are also free.
You will never permantantly get rid of the addware and spyware. When yo sure the net, stuff gets addded to your hard drive. Even sites like CNN, USAToday, MSNBC install this stuff on your computer. Why do you think the online versions of these newspapers are free? Cause the put add stuff on your computer in hopes that you will buy something someday!!!!
Tuco: When you have to shoot, shoot, don't talk.