In Windows 7 and Vista, Windows Explorer has a Favourites list in the left-hand pane. By default it includes several folders, although they differ between the two versions of Windows. To make the Favorites list truly useful, you'll want to add the folders you use most often.
To do this, simply navigate to a folder you regularly use, then right-click on the Favorites link itself and choose Add current location to Favorites.
See also: Windows 7 Advisor
To remove an item from the list, again right-click on Favorites and choose Open in new window. This displays the list of shortcuts, which you can delete at will. Since they are just shortcuts, you won't delete the folder to which it links.