I've had loads of antivirus and the free one are not that great, on numerous occasions I would get the odd virus creeping in especially avg! avast is good at you can scan at start up of PC. Jasper sky was great until I got a key logger which could not be removed , that's when I used norton 360 and have done ever since with no issues to PC slowing down and catches everything. Also use malware bytes it's free and catches everything, can be used with any AV