Keeping your Windows PC secure from viruses and spyware can be both difficult and expensive, and some of the popular security suites out there are known to slow down computers.

Yes, there are quite a few free antivirus software programs available on the web but they are often designed to convince you to purchase the professional edition and thus nag users with prompts to purchase the commercial version.

If you are looking for a non-bloated software that doesn’t nag you at anytime, try Security Essentials - it’s one of the best anti-virus and anti-malware programs that is lightweight and absolutely free as long as you are running a genuine copy of Windows XP, Vista or Windows 7 on your computers.

Microsoft Security Essentials is a capable application that has been streamlined to run efficiently even on netbooks or older computers with low resources. But even on a modern computer with multiple cores and several gigs of ram, a lightweight antivirus solution will definitely make your computer a bit speedier. Security Essentials is also ideal for running in virtual environments such as the new XP Mode for Windows 7.

Microsoft Security Essentials is not just lightweight but easy to use as well.  After downloading the small installer (it’s less than 10 MB in size), installation takes less than a minute and it will immediately start protecting your computer from virus attacks. When Security Essentials is scanning your computer for problems, you can still work as normal as the software has been designed to use a limited amount of system resources if a user is using the computer while a scan is in progress.

Also see: Download Portable Anti-Virus Software for USB

The software will automatically download new definition from the Internet through Windows Update, and these will be installed on the computer without requiring user intervention. Additionally, Security Essentials is the first product to make use of Microsoft’s Dynamic Signature Service that enables the program to get the latest definitions as soon as their computer suspects a threat.

Although viruses have traditionally been the main security concern in Windows PCs, the security landscape has changed and computers users now have to face threats of rootkits, malware, and spyware in addition to viruses. Windows Defender was designed to keep adware and spyware off your computer but Security Essentials works against most types of threats. The software has received favorable reviews and one of the testers noted that Security Essentials detected all of their sample threats correctly without giving any false positive reports.

Stay secure without sacrificing your computer’s speed or your hard-earned money. Microsoft Security Essentials replaces both Windows Live OneCare and Windows Defender.

Related: List of Online Virus Scanners