I really love the preview feature of the Windows 7 taskbar. There's only one reason I don't use it more often -- it takes a relatively long time to display the actual window.
There is a registry trick (widely found on Google) to reduce the delay used by general menus, and make the submenus open instantly when hovered upon. I'm wondering if there's a similar trick that can be used for the Windows 7 taskbar's previewing.