Windows 7 does not let folders to be pinned to the taskbar. If you like this option, here is how to do it:

1) create a new text document (right click on desktop and choose ‘new’-'text document’)
2) press the window button and type ‘folder’, click on ‘folder options’-'view’ and uncheck ‘Hide extensions for known file types’
3) now rename the new text document to ‘name of folder you want.exe’ and ignore the warning about the extension type change.
4) Now you can drag the new ‘name of folder you want.exe’ to the taskbar.
5) Next, browse to the folder you want, press ‘Shift’+'right click’ and choose ‘copy as path’
6) Now right click on the new taskbar folder, choose ‘properties’ and paste to the ‘target’ the folder path. click ‘ok’ and you are done.