IIRC NT5 is Windows 2000. Windows XP is NT 5.1.

Preemtive multitasking means the OS designates which process (or thread or whatever) runs on a particular processor. This scheduling is the whole trick. Scheduling on XP still sucks IMO. Why? I keep hitting the same thing.. Processor indicates 99% idle but the OS doesn't respond to clicks, keys or whatever... Until after a few seconds then everything happens in the order I clicked... I never ever experience that on my BSD machine..

Hotmail used to run completely on BSD I believe. Then MS bought it. They tried to migrate to Windows 2000 but had to stop because W2K couldn't handle it. AFAIK now only the front-ends are windows machines but the backend is still bsd.