1) Left Click Start Menu\Control Panel\
2) Double click on Administrative Tools
3) Double click on Computer Management
4) Under Computer Management, left click on Disk Management.
5) Right click on the Drive that you want to change the drive letter for and select "Change Drive Letter and Paths...".
6) This will then open a dialog box, that will allow you to select the Drive. Once the drive that you want to change is selected, click the Change Button.
7) You will now see another box pop up, that shows a Pull down menu on the right hand side. Select the drive letter that you want to change this drive to. Once you have done this, then click OK.
8) You will see a dialog box pop up asking you to confirm with the following message: "Changing the drive letter of a volume might cause programs to no longer run. Are you sure you want to change this drive letter?" Yes or No? Click YES.
9) Now close out of all other programs and your drive will now have the correct drive letter.