In Windows 7, it’s been annoying me for a while how the windows explorer item on the taskbar always default to my libraries, as on most systems I use they are empty.
You can change the location by holding shift and right clicking on the taskbar item so you can select properties in the context menu (If you’ve already got explorer windows open, you’ll need to right click the taskbar item once, then hold shift and right click on the Windows Explorer entry.)
Once in the properties window, if you set the target to the following, it will open ‘My Computer’ by default…
%SystemRoot%\explorer.exe /e,::{20D04FE0-3AEA-1069-A2D8-08002B30309D}