I believe Avast is the best antivirus going,but my computer kelp misbehaving I run a full scan every day for five days,and avast kelp saying no problems,so i downloaded a malware program called asquare,and updated it,then run a full scan,and low,and behold two virus,and three traces showed up,waited three days,and updated it,then run a full scan again,and a very dangerous virus showed showed up,what I'm saying most antivirus programs don't support xp any more,they write for vista,and windows seven..even if avast is the best,you need too run a different helper program too be safe...which one is your choice,but run a good one..regards tony and yes i have the right version,but it's still listed as asquare where i downloaded it,then it updated too emsisoft,one virus high risk was called aolddailer.dill,soon,as i saw i could i deleted the others.