Unless there’s something very unique about the camera, the USB is only going to transfer still images off the memory card (and possibly supply a low-res webcam function) - you won’t be able to transfer video through it.

There should be a mini-firewire/mini-DV/iLink port hidden under a flap - that will connect to a firewire port on a desktop, or an older laptop.

If you don’t have access to a firewire port, your existing S-Video/AV cable is still your best option.

Unless anything magical has happened recently, a firewire to USB will not help you for video capture.