As whole I have 3 anti-virus in my pc

I use spyware doctor .. its spy ware cum anti-virus.. its really very good...
and AVG 7 is also good..
mcAfee anti virus.. its good too....

the worst anti-virus i have seen is the Norton anti-virus... its slows down the system...its really the worst anti virus..



I want to know your opinons what do you think about these anti-virus..

Thanx