You would be changing the assigned drive letter not location there. With XP or Vista you would go into the "Control Panel>Administrative Tools>Computer Management>Storage" section and open up the Disk Management tool. Once you see the external drive in a small window where the list of drives have a long bar for each one you simply right click on that drive's listing there and choose the change drive letter option. The list of letters with no other drive using them will then be seen in a drop down list there. Simply choose the new letter and answer yes on the confirmation.
