As I said in my first post, USB is just not good enough to transfer video at full quality. You will get lower quality pictures with probable dropped frames which will make fast movement jerky
Firewire aka iLink, ieee1394, DV-port (all the same just different names to make our life easier

) is the only way to go. A firewire card that includes the required cable to connect to the cam should cost you under £20, so not too expensive and very easy to add to the PC. The difference in quality with this connection compared to USB will IMO be massive.
Mark.