Hi,
AFAIK, both standards are quite similar when it comes to speed?
Actually firewire is up to 800Mbps now, although your computer will probably only have 400 against USB 2 which is 480. (I think, hehe, Its something like that)
As for which is better for a camcorder, naa neither, I have just got a DVD camcorder (cheap) a Hitachi 230E, then you just take the DVD (-r or RAM) and stick it in your computer or DVD player and your done, beat that for performance. :-P