The SiS 964 Southbridge supports USB 2.0, but Windows may fall back to 1.1 without the correct SiS USB 2.0 filter driver. Install the "SiS USB 2.0 Enhanced Host Controller" driver (available on DriverGuide). Then, in Device Manager, delete all "Universal Root Hub" entries and scan for hardware changes.
When you first turn on the computer, press the Pause/Break key during the initial boot screen. The model number often appears at the top or bottom of the screen. n1996 motherboard drivers