Introduced in September 2009, Microsoft Security Essentials (MSE) replaced Microsoft's antivirus subscription service (see Windows Live OneCare) and its Defender antispyware software (see ...

Tech expert Kurt “CyberGuy" Knutsson says using outdated computers and software leaves them vulnerable to security risks and malware.

Microsoft Security Essentials 4.0 does a decent job protecting a clean PC, but in testing its cleanup of already-infested systems wasn't thorough. You can get better protection for the same price.