Anti Virus programs fighting each other.

I had three anit virus programs on my computer, all free. Avg, IQorbit (sp) and not sure about the other. My computer was taken to an expert and it was cleaned up completely, I had put my documents on Flash Cards. I was also told that the expert uses the free AVG for anit virus control on his personal computer. So now that is what I have. I also had the free Advance Systems Care for some infections (not an anti virus program). For some reason I am having trouble finding it again. Would appreciate comments.