CPU Usage on all 32bit Windows OS

A simple to use class that returns the current CPU load usage of the system as a percentage. Works with all 32bit Windows operating systems (9x, ME, NT, 2000, XP) and also works with multiple processors. I couldn't find any CPU usage code on PSC that would work with XP, so I had a hunt around the web and came across the NtQuerySystemInformation API. The class detects the OS and uses the appropriate CPU usage retrieval system.