You never said it was a laptop - hence the reason I covered my ass by saying 'if possible'
well I'd go looking for updated chipset / usb drivers. Does the board use an Intel chipset? Their drivers are easy to find!
If you look at the usb branch in device manager, does it actually say 'usb 2' anywhere? It probably will do if it's usb 2. Mine shows up as 'Intel(R) 82801EB USB2 Enhanced Host Controller - 24DD'. Microsoft actually do a little tool to show you how your device is connected. It's called 'USB View'. I'm sure you can find it if you search google.
Then again, windows XP (if that's what you're running) should pop up a message if you connect a usb 2 device to a usb 1 port.
When you're ripping, I assume the buffer is always at 0%? If it's not, that would indicate the problem was actually with something to do with the hdd.
Can you copy stuff off the dvd using explorer any quicker, or does it always take ages to do anything with the drive?