For most people, XP patches will be unobtainable through legitimate channels



From Computerworld:

Well, it used to anyway. Microsoft appears to have decided that it wasn't getting enough customers for the program, so it cut the price. Companies have told Computerworld about great deals that Microsoft agreed to at the last minute, including one said to have gotten its XP patches for the bargain price of $25 per machine.

I know what you're thinking: "There's no way I could afford $200 a PC for patches. But $25? Sign me up!"

  Steven J. Vaughan-Nichols: Here comes the black market for XP patches