I'm having the same problems connecting my JVC GR-D31EK through Firewire on XP.
Installed the card and checked device manager and it shows up there, using a brand new 6-4 pin cable and nothing. no little bubble with "Found new hardware" tried switching everything off, plugging in cable, turning camera to "Play", then turning on computer and still nothing.
Tried on a different computer with a different cable and still nothing.



Anyone found a way round this?