Just answered a question from a buddy about Windows Live One Care. The Live One Care product is being discontinued and will be replaced by Microsoft Security Essentials.
Microsoft Security Essentials is in beta right now. From what I understand Microsoft Security Essentials will be a free solution.
More info here: http://www.microsoft.com/security_essentials/.
From KezNews: “…the final product will be available only before end of 2009...”