What, that their active kernels are riddled with random third-party code, uncontrolled by the people responsible for the kernel itself? I find that unlikely. Not impossible, mind you, just very unlikely. In the case of Linux, you might want to alert Torvalds to your concern.
If (a) 85% of Windows crashes are due to the fact that random third-party vendors' drivers, etc. are hooked directly into the OS kernel by design/necessity, -and- (b) Linux, BSD, OS-X have the same issue, then one would expect Linux, BSD, OS-X to crash as often as Windows.
Doesn't happen that way. I know, I run them all, all the time. My Windows boxes (which are generally kept pretty clean) require restarts many times more often than the others. My OS-X and Unix boxes run for many months at a time without a hang (restarts are generally for security updates that require a restart).
Sure, applications hang in Linux and OS-X, but they rarely corrupt the kernel. The issue in question is whether random software vendors can crash the system. In Windows, their drivers are generally running at Ring0, which tells you all you need to know about why Windows crashes many times more often than the others.
A new Windows architecture can learn lots from the others. Or better, as Apple did, stand on the shoulders of a giant and get a head-start without having to re-invent the wheel.
3rd party kernel mode drivers can crash the OS. To get around this you can use a microkerel - which is slow - or move as many as you can to user mode - which is what vista has been pushing people to do.
Google nvidia linux panic sometime.
You appear to not really know anything about the changes in vista - have you actually studied them or are you going on 2nd hand information?