AVG Is great, but being "man-made" is not at all fool proof...
I use AVG exclusively but I also use an assortment of other AV software,
1.Avast
2.Mcafee Stinger
3.Trend Microclean
All decent programs but not perfect..
I have heard of one thats so far seems to be perfect so far NOD32, I have never tried the program but I have heard nothing but great reviews....
So theres a few out there, but do not trust just one...