Of Microsoft and Symantec, I'm not sure who I trust least. In any case a Microsoft virus checker wouldn't have to - indeed wouldn't benefit from - seeking attention. That, in it self, would probably lead to a better product. There are other technically sound arguments for letting Microsoft deal with security issue, such as the fact that they know how the system is built (At least in theory).

This was corrected: http://www.microsoft.com/downloads/details.aspx?displaylang=...