Two years after trying to build a consumer antivirus business, Microsoft has decide to throw in the towel.The software vendor said Tuesday that it will discontinue retail sales of its Windows Live OneCare product at the end of June next year, and instead offer Windows users free antivirus software, code-named Morro."In order for us to focus on delivering this new security solution to millions of customers around the world, we have decided to phase out Windows Live OneCare," Microsoft wrote in a blog posting Tuesday.Morro is expected to ship by the end of 2009 and online OneCare sales will be gradually phased out sometime after that.Designed to appeal to people who have not bought antivirus software, Morro will use less system resources than OneCare. It will also have fewer features. It will protect PCs from malicious programs such as viruses and Trojans, but will not include the systems management and backup capabilities that come with OneCare.The free antivirus software will be available in the same markets where OneCare is currently sold, Microsoft said. OneCare subscribers will continue to receive support through the end of their subscriptions.Microsoft shook up the consumer antivirus market when it began selling OneCare in May 2006. Antivirus vendors worried that Microsoft would use its desktop monopoly to push customers to the product, and OneCare itself represented a reinvention of the antivirus category, with its backup and management features and its three-user licensing model.But the product did not perform well in reviews and ultimately failed to challenge the dominance of antivirus leaders such as Symantec and McAfee.