Windows exploits are not found by looking at a sample of code, or even *most* of the time on purpose.
Right, so only hax0rs knows about them, and can use them

. In open source, many people looks inside the source, and the problem is fixed very quickly. You don't have to wait for MS to make another security fix.
I'm not some Linux/GNU zealot, i use WinXP and it's a good OS imo.
So, let's not start another OS war, please.