The secret of whether a Windows XP machine has USB 1.1 or USB 2.0 is revealed by whether it has USB enhanced host controllers. If it's enhanced then it's 2.0, otherwise it's 1.1.
Control Panel → System folder → Hardware tab → Devices → Device Manager → Universal Serial Bus Controllers folder
See http://www.usbman.com/Guides/checking_for_usb_2.htm.
Tarim / April 2008 / for Duncan Speakman