For beating spyware on your computer it is OK to have a couple of programs operating for you .. In fact, recommended.
Lavasoft Adaware is a highly recommended program as well ..
Using the both together is a good choice ... also free ...
http://netforbeginners.about.com/od/...alware07_2.htm
You need to run the program at least every couple of weeks though, and keep it updated .. it's not something to install and just leave .. you need to operate it .. regularly ..
Free Anti-virus software - Grisoft makes AVG and it's reliable ..
The most important thing you must remember is to keep your programs updated.
With free antivirus software you normally must do your own updating, everyday. Usually one update comes in per day at a certain time, but throughout the rest of the day you must take updates manually.
And this should be done everyday, if not two and three times a day.