Honestly, these kids...
Go to Control Panel\Administrative Tools\Computer Management\Storage\Disk Management\<your disk>\Change Drive Letter and Paths and change the drive letter assignation.
This will be then be sticky and survive reboots and other drive plugins.
Mac
Edited to add:
DriveLetterView -
DriveLetterView - View/Change/Remove drive letters assignment in your system and
USBDLM -
USB Drive Letter Manager - USBDLM are both free and make it easier.
Another approach would be to use Symlinks, Hardlinks, Junction points or Volume Mountpoints.
You do however need to do a bit of homework on how the NTFS filesystem works....
Junction Link Magic -
Junction Link Magic and
Link Shell Extension -
Link Shell Extension both free, provide an easy way to handle these.