If you guys actually knew anything about computer security, you'd realize that any anti-virus defense requires daily updates, for constantly emerging threats. You can't just install anti-virus, and be protected, without getting new updates known as "signatures" that allow the anti-virus software to protect you from threats that appeared after the original anti-virus software was installed.
That said, I think Microsoft should concentrate on securing their operating system, and assist rather than replace existing anti-virus vendors in providing daily anti-virus protection. Users need to rely on a multi-vendor, layered approach to securing their systems, not a single vendor that can be a single target for attacks.
Stating the obvious gets you no points with anyone here. Sun, RedHat, and Apple all make a product good enough that you don't need to subscribe to a service for an extra 50$ a year. Seems to be a task beyond Microsoft
That said, I think Microsoft should concentrate on securing their operating system
Welcome to the party, you're a little late but were happy you're finally here.