USBDLM is a Windows service that gives control over Window's drive letter assignment for USB drives. Running as service makes it independent of the logged on user's privileges, so there is no need to give the users the privilege to change drive letters.
It automatically solves conflicts between USB drives and network or subst drives of the currently logged on user.
Furthermore you can define new default letters for USB drives and much more.
* Bugfix: With five or more drives in the balloon tip the word "drives" was missing in V4.5.5
* New: Multiple DeviceArrival events for the same device are ignored
Tools and Utilities
Product page: here