Maybe I'm going against the grain here, but I'm glad Microsoft is going to release free antivirus software. I don't want to worry about choosing one of these third-party products and having my browser hijacked or whatever.
Agreed. This is one of those things that really should be dealt with on an os-level. They could push updates through the same channel as the os security patches.
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).