I think you have two possibilities
1) Locate and use a computer that has a firewire port (or can be somehow equipped with a working firewire port).
2) Use the camcorder's AV-out connected to an "analog/digital converter" which connects using USB to the computer. Elgato, Roxio, and many others make these. Since the Sony DCR-HC38 is a standard definition video camcorder, the reduction in video quality as it steps through analog and through USB will not be so obvious.
USB-to-firewire cable/adapter/converter things will not work to do what you want.