Well, there's a piece of Apple-championed technology, Firewire, which doesn't care what OS you're running because it has direct path to the DMA controller, and can read and write physical memory.
This is not true. OSX locks down the FireWire ports to protect system memory. I am not sure exactly how this works but I believe it's firmware/driver dependent and Windows usually lacks the drivers to force the firmware into a protected mode. FireWire having direct access to the system ram is not a requirement of the 1.0 spec, it's a stupid implemention decision by chip designers.
