Not all antivirus products are good. There are many that actually slow down your computer and still do not protect you against virus, malware and cryptovirus intrusion.
RevelationSky provides the best-of-breed, proven and independently tested antivirus solution Bitdefender and will install and configure it for you either onsite or remotely.
Don’t risk your data on a free solution. Having one is better than nothing, but they provide very limited protection whcih in this day and age is not sufficient to ensuire that your computer is not compromised.