I'd say OS X is more secure than any version of Windows both in concept and implimentation. It is a real slick and sound version of Unix and it improves on the already excellent security of Unix with quite a few tricks of it's own. The amount of vulneralbilities patched is not a true measure of how secure a system really is. Windows fails because, even though it can be secured, this ends up being a real pain to the user while it is graceful and transparent in OS X so users aren't pained by security and don't turn off key security features because they are annoyed by them. They don't even notice them at all which is the way good security should work.
