How to disable usb port on your system?

For security purposes, one might need to disable the data transfer between windows machine and usb key.How to disable the port? Its simple.
Goto Regedit>>HKEY LOCAL MACHINE\SYSTEM\CurrentControlset\Services\usbstor>>find start>>double click on start value>>input data value = 3 (default in Hexadecimal). That will disable your USB port.
Be careful since this disables your USB modem too. I have not found any selective removable media enable/disable option. Please share if you know.