There is no Firewire to USB, but there is ilink to USB. This is a Sony cam right? It should have come with that cord. If not, it cost about 20 dollars at Best Buy. Your best bet is to go for the firewire card. I run a G4 DP system and I use firewire for video editing (final cut pro). It is sooo much better and USB. With USB the video and camera itself will be VERY choppy. Looks like
Good luck. Ohh and if you are using that windows XP movie maker...well, IMO it is gay. It's Microsofts knockoff of iMovie.
Go online and download a better video editing program. Limewire, Kazaa (?)...