>Sorry, I don't use AD with Win98SE, and this doesn't work. So it appears tied AD and not the OS.

I don't have the AD turned on in Win98SE either, but this feature still works. Here's something else: when all tasks are iconized, clicking on the task bar icon of any given task toggles it between visible and iconized. When you minimize the current task's window, the previous top task comes to the top only if its not iconized (as expected).