Vista does have protection

"It is very easy to do an absolute sector write to the hard disk under Vista (you need elevated admin rights but no special APIs...)"

That's exactly what UAC is there for. To stop non-priviledged applications from accessing certain administrator APIs. If you disable UAC, you lose that protection. If you're stupid and click "Allow" to unknown applications, then - well - you're stupid and would probably do the same on any machine, regardless of the OS.

I'm sure if I said the following, I'd get flamed by all the Linux (and Mac?) crowd out there - but essentially it's no different:

"It is very easy to do an absolute sector write to the hard disk under Linux/OSX (you need to be root to do it but no special APIs...)"

In Vista, you need to be elevated - in Linux/OSX you need to be root.