Taskbar Button Manager is a simple utility that helps you arrange the buttons on your Windows taskbar in any way you want by using drag and drop. Moving your task buttons is very easy, no hotkey needed. In addition to drag and drop you can also use a special program window for moving the taskbar buttons. You can hide running programs too, so they don't show on your taskbar. The program works in all situations – even when the taskbar buttons are grouped or when the taskbar is not located in the standard bottom area of the screen.
O Gerenciador de Botões da Barra de Tarefas é gratuito, requer registro.
p .: por que você não usa o agrupamento (propriedades da barra de tarefas)?