Click on the Start Button and type in Regedit and hit Enter.
Navigate through HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control.
Right click on Control and select New and then Key. Call the new key StorageDevicePolicies.
Right click on StorageDevicePolicies and select New and then Dword. Call the new dword WriteProtect.
Right click on WriteProtect and select Properties. Set the value to 1 and hit OK.

The computer is now configured to disable writing to USB storage devices.