tell me the best anti virus for computer ??

I don't really know if there is a best scanner. There are many good ones, norton is among them. Another good one is F-Prot from frisk software and AVG is good, as well. I've discovered that just one doesn't seem to be enough, I recomend having 2 or 3 good scanners. If one misses something another may catch a stealthy trojan or virus.

i was using NORTON also until i found ESET NOD32 i can say that it's the best.