How to disable specific usb ports in a windows xp 64 bit

[JR1010]

I have been assigned a task for disabling the USB post so that no employee can use USB drive or any other external hard disk to connect to the machine. This will maintain the security and authenticity of the company's data.
Right now there are six USB ports on a single machine and when I tried to lock the USB port from BIOS it locks all the USB ports. This means that even the keyboard and mouse connected to the USB ports will not work.
So please tell me how to block a specific USB port. Would like to block only 4 ports and leave 2 ports open for mouse and keyboard.

Thanks!

 

[WyomingKnott]

A) That won't work; someone could just unplug the mouse and use the keyboard to copy.
B) There is a security policy that disallows either USB drives or only writing to USB drives, I forget which. Interested?
C) Epoxy the mouse and keyboard cables into place and pour epoxy into the remaining four ports.

If your machines are connected to a network, none of this will improve your security noticeably, just prevent casual malfeasance.

Edit: here's a quickly-found bit on the security policy: http://www.windowsecurity.com/articles/control-usb-devices-group-policy.html