The following registry have been change for the USB port read only for USB thumb drive

 

Reference:
http://www.petri.co.il/disable_writing_to_usb_disks_in_xp_sp2.htm
http://www.howtogeek.com/howto/windows-vista/registry-hack-to-disable-writing-to-usb-drives/
http://diaryproducts.net/about/operating_systems/windows/disable_usb_sticks
http://support.microsoft.com/kb/823732
http://www.petri.co.il/disable_writing_to_usb_disks_in_xp_sp2_with_gpo.htm

The following registry have been change for the USB port read only for USB thumb drive