ide to usb

I had an internal harddrive. when i got a new computer i bought an external case for it and made it into an external harddrive. but windows xp will not reconize it. In a nut shell it was internal and now its external and not working. i get unknown device when i hook it up. the external case is a VIO 3.5 external case. serial ATA. and its usb hook up with external pwr source