100GB wont mount

I just got a LaCie 100GB portable external hard drive, i pluged it onto my laptop and it does nto work. My friend has teh same exacte modle but its 80GB and it works fine. I use both the Firewire and USB and it does not mount, there is a red light infront but nothing on the desktop.

Note i dont want to have a power line, it should be powred from the firewire or USB.

I just tryed it and it works with my G5 but does not work with m y 17" PB. I am not sure but does it have to do with it not getting enough power?