I'm really excited about this announcement. This is a great step forward in making protection of your PC available for all. In the second half of 2009 we will be releasing code-name Morro that will protect customers from trojans, viruses, spyware, rootkits etc.
The big thing for people to realise that with technology it is always a two part problem, there is the technology and then there is the human element. Hackers etc. are using social engineering tactics to gain the trust of the user to perpetrate hacks and unauthorized access, so we need to also be self aware of this tactic.
However to make security protection free for all means there is no reason not to have the technical element of your software secure.
Microsoft to offer free consumer security suite | Security - CNET News