RE: Q. Alternative anti-virus prog. to WinAntiVirus?

To the person that responded first with 3 free download info. Is it good to use all 3 simultaneously or just pick one? WinAntiVirus sure got me. I paid for the prog. then later they recomm. "DriveCleaner", so I installed that. After running DriveCleaner, full sys cleanup, states "system good", but if run again, always there are more violations found! Makes no sense. Thanks for all the good answers....I am very grateful.