Free security software to protect your PC from malware
Security software is one of the first and best things to install on your computer. An unprotected Windows computer can pick up a virus on the Internet in under a minute.
Even Macs aren't immune to viruses. A recent Trojan outbreak infected more than 600,000 Macs worldwide!
Protection doesn't have to be expensive, though. Research shows that free antivirus solutions are just as effective as paid programs.
Antivirus
There are tens of thousands of pieces of malware circulating on the Internet, including viruses, worms, Trojans, dialers and other monsters. These pose a serious threat to your security. Antivirus software can counter this malware.
You should only run one antivirus program on your computer. If you run multiple antivirus programs, they'll conflict. Make sure to keep it updated, as virus definitions are constantly being added.
A firewall hides your computer from probing hackers while you're online. It also watches your computer's network traffic to watch for suspicious activity. As with antivirus software, only run one firewall program at a time or they will conflict.
Windows 7 and OS X both have decent built-in firewalls. The Windows firewall is turned on by default. To turn on the firewall in OS X, go to System Preferences>>Security & Privacy.
Spyware and adware are other big threats to computer security. Spyware tracks your Web surfing and reports your interests to a computer on the Internet. Adware sits on your computer and feeds you ads. Both spyware and adware will slow your machine.
You need programs to keep spyware and adware from taking root and you need other programs to annihilate spyware and adware that collects on your computer. You should use multiple anti-spyware programs on your computer. Unlike antivirus software and firewalls, they won't conflict.
No system is entirely safe from malware. The above programs can remove most infections, but there are some infects that just won't go away. Here are some powerful last-ditch programs you can use to clean up your system.
Microsoft's Internet Explorer 8 and earlier is rife with security holes. IE9 is much better, but it isn't available on Windows XP. If you haven't upgraded to IE9 on Vista and 7 I strongly recommend you do so. If you want an alternative to IE on any version of Windows, here are some browsers I recommend.