First (and easiest) things first: are you using the same cable? Does it work with another Firewire device? How about the port on the iBook? Can you confirm that it is working properly?
I was once having fits with an factory-installed Ethernet port on my 7300/200... It turned out to be a bad port; adding another Ethernet port by installing a PCI card did the trick, cheaply. The 7300 was way beyond its warranty expiration date by the time I tried to use the bad port...
I also had problems with a 200GB FW drive that was caused by a narrow gauge cable that was not capable of handling the transfer dynamics of the large drive.
Sometimes a FW drive will not mount on one machine even though it works with another. It's probably a FW drive chipset issue, but I can't offer a fix for that problem.