Use firewire.
1) You have better control over (Play/Pause/Re/FF)
2) Faster data Transfer.
3) Compatible with DV cameras.
With USB, I was never comfortable, Firewire always worked. Except with the new HiDef (HD) camera from Sony, The quality is superb. but for some reason, I get that slow motion effect in some parts of my movie, althou it looks amazing on TV set.
What camera *Model* are you currently using?