Microsoft Security Essentials designed to cover the basics

Microsoft has admitted Windows users should install antivirus above and beyond its own Security Essentials, describing its protection as merely a "baseline" that will "always be on the bottom" of antivirus software rankings.

Microsoft launched Security Essentials in 2009, raising complaints from antivirus rivals that such software shouldn't be bundled with Windows for competition reasons.

However, the most frequent complaint about Security Essentials is that it's not good enough: it flunked a pair of tests earlier this year - including one from Dennis Technology Labs.

Now, Microsoft has said it sees Security Essentials as merely the first layer of protection, advising customers to use additional, third-party antivirus - although the company stressed that wasn't because the product wasn't good enough to stand on its own.