First Microsoft puts out Microsoft Defender, which is free but do not have central management. Its based on their purchase of Giant Software
Now they have the beta of Microsoft Forefront Client Security, which looks like it does both anti-spyware and anti-virus with central management. I’m sure its going to have a cost. This product is based on the purcahse of Forefront software.
Which one will work better and be around for the long term, my guess is the one that will have a cost involved.