The best method to check and protect a computer for computer viruses is to use an antivirus program. There are many different programs to choose from, but the better-rated brands are Kaspersky, Symantec, Trend Micro, and MSE. You can get just the basic antivirus program or a full antivirus suite, which often include other types of protection beyond just virus protection. You can also try using a free online virus scanner to check for viruses on your computer.