As a long time Mac user, one of the more solid companies I've dealt with is OtherWorld Computer (
www.macsales.com). They make Firewire enclosures. I also highly recommend their RAM. I just bought one of their enclosures as a replacement enclosure for a LaCie external firewire disk which died (drive was fine, case died). Been great so far. Only thing is, the blue power light is piercing. I had to cover it up.
PS. Definitely get Firewire. It's just better technology for the task at hand.