It is very easy to get free antivirus software from internet. Mostly, the companies which develop antivirus software provide a free evaluation version of antivirus software for public use. This encourages the customers to acquire the full version to safeguard their computers from virus.
It is interesting to note here that whichever antivirus program you use, it is recommended to have just one antivirus installed in your PC. You will be surprised to know that if multi antivirus programs are installed, clash of files will occur and will lead to poor performance of your PC.
Antivirus software should also have the competency to spot the new virus on internet. So, it would be good to purchase the software which can detect these new viruses quickly. Sometimes, some virus creators intentionally repack an identified virus with a different archive or compression to cheat the signature based scanners. So, the software should be competent to decompress such files for virus scanning.
Mostly, the free antivirus software charges high in spyware and adware category. This happens due to unavailability of the specification in the free trial version, so you have to acquire the complete version of the software to enjoy the service. You should also see to it that the space of operation needed for your antivirus is sufficient.
As a result for this free antivirus evaluation, it is checked thoroughly to determine that how well this software can remove a virus. This is checked because most of the free versions of antivirus software do not have this facility and you need to acquire the complete version to get this facility. It you want to remove it manually, you need to check the database of the vendor to detect the virus. Then you have to remove it on your own.