When we click the Explorer icon on Windows 7 taskbar, by default it opens the Library. But, it is a matter of fact, most of the users need to open Computer (My Computer in older versions of Windows) more often to access different partitions or external drives.
Instead of pinning a new shortcut to Computer or the partitions in the taskbar; we can tweak the opening location of this explorer icon on task bar. The method is easy.
Steps to get my computer on clicking the explorer icon on taskbar in Windows 7
First, right click on the Explorer icon on the taskbar in your Windows 7:
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You can see the Windows Explorer in the above screenshot? Again right click over it :

Click Properties as shown in the above screenshot. You will get Properties Windows, and you will notice, in the Target field under Shortcut tab, the target is as follows:
%windir%explorer.exe
Yes, this is the default location to open Windows 7 Library location. You can copy and save it in notepad, if you think to revert back, just replace with the above one.
Changing the target of Explorer icon of taskbar to open My Computer
Select all the target and delete it. Paste the following:
%systemroot%explorer.exe /e,/root,::{20D04FE0-3AEA-1069-A2D8-08002B30309D}
Click Apply and then OK. Now, on clicking the Explorer icon on Windows 7 Taskbar it will open My Computer instead of Library.
Changing the target of Explorer icon of taskbar to open other location than My Computer
If you like to open other locations, instead of My Computer by clicking the explorer icon on taskbar, for example a particular partition, you can do it by typing / copy pasting the following line in that Explorer icon Properties Window Target field:
%SystemRoot%explorer.exe /e,Letter_of_Drive_in_capitals:
Change the red text with, E if you want to open E partition, like this:
%SystemRoot%explorer.exe /e,E:
