xascendent is correct -- under NT the operating system traps that key sequence before you'll ever see it. Keyboard drivers run in Kernel space (to protect the operating system from errant code), not user space. Buy a copy of "Inside Windows NT" to see how this works.
Writing a replacement won't be fun or easy (kernel-mode drivers run as a service, and are debugged using the text-mode kernel debugger on a remote machine connected by a serial port).
Chip H.