1. log in as administrator.
2. Click Start --> Control Panel --> Administrative Tools --> Computer Management.
3. From the left pane of the Computer Management window, click Disk Management.
4. Right click the drive that you would like to change.
5. Select "Change Drive Letter and Paths" from the resulting menu.
6. Click the Change button.
7. Select a letter from the drop down menu.
8. Click OK.
9. Reboot your system for this change to take effect.
Note: You will not be able to change the letter of the boot partition.
