On your desktop

Right click on teh "My Computer" Icon
Choose "Manage" then pick "Device Manager"
On the list on the right hand side, click on the "+" sign
to the left of the IEEE1394 Bus Host Controllers

This will give you the Chipset on your Firewire Port

e.g. Texas Instruments OHCI,, or VIA or SIS (SIS is not supported by Digidesign or Tascam)