Yes, you can, but it must be plugged in into the same USB port every time.
The procedure is:
1. Right-click My Computer, Manage
2. Click "Disk Management"
3. Find your USB drive in the list, and right-click to the partition, chose
"change drive letter..."
4. Specify a drive latter, best a drive letter like "T:", because it will
not be moved when a new device comes along to the beginning of the drives
list.
Best regards,
