Microsoft ain't stupid.
First, they save money with sloppy coding and patching. Then they let users "beta test" released versions (i.e., YOU find the errors, then report them). Then they charge for help. Now they want to sell you anti-spyware to plug the holes in their sloppy code.
If they screw up, they should fix it. Until we get Longhorn, we'll have to put up with a patched system.