I am a great procrastinator...
Being a MSDN Subscriber, I got Windows 7 when it went RTM and which is when I initially installed it as a dual boot with Vista. The mild click button worked as Tim Sneath described in #19 of his blog: Tim Sneath : The Bumper List of Windows 7 Secrets
'19. One More of the Same, Please. Iíve seen a few folk caught out by this one. If youíve already got an application open on your desktop (for example, a command prompt window), and you want to open a second instance of the same application, you donít have to go back to the start menu. You can simply hold down the Shift key while clicking on the taskbar icon, and it will open a new instance of the application rather than switching to the existing application. For a keyboard-free shortcut, you can middle-click with the third mouse button to do the same thing. (This trick assumes that your application supports multiple running instances, naturally.)'
For some reason I reinstalled Windows 7 about two months ago and did something different and now when I use the middle click, it simply displays the task list. Anyone know how to make the middle click return to the default behavior?