It is essential that your PC is adequately protected and should have a firewall AND anti-virus software as a MINIMIM.
This software should always be current and up-to-date. It is possible to get an Antivirus/Firewall package from most security software vendors. This is often called "xxxxxx Internet Security" wher the xxxxxx is the name of the vendor.
We highly recommend:
These are paid for (subscribed) packages where you will need to renew every year. We do recommend using a paid for package rather than a free anti-virus/firewall as you tend to get other protection such as anti-malware, anti-spyware and anti-rootkit protection bundled.
However there are also a lot of good "free" security applications out there:
These are recommendations only and whilst this software is all tried and tested and found to be very reliable we do not hold any responsibility for any damage that the above-mentioned software may cause to your machine. If in doubt, seek more information from the software vendor.