What happens if 2 antivirus software in 1 computer?

February 23, 2009 6:04am CST
Hi I just want to know if 2 antivirus software installed in a 1 pc what happens? I have downloaded 1 avg (free)antivirus software 2 days back and my hubby installed quickheal(paid) antivirus software today. now I want to know shall I remove avg. What happens if I keep both. Thank you