Can't see USB devices Powerbook G4


I was told that MAC would see USB devices that XP would see. I have tried 2 devices:
external fujitsu 80gb hard drive installed in an Xannet USB 2.0 case.
I formatted to FAT32 When I plug in no luck.

Also a Belkin 8-1 Media Reader, nothing!

On the Belkin site it lists device as Mac compatible.

Is there a trick to enable USB support on the G4 I am missing?
I have the same problem with my hitachi drive in an icy box enclosure. It works if I connect the other usb cable that connects to enclosures power port. The problem seems to be the lack of power from a single usb2 port for the disk to work. Which is not right since the drive works on any PC without problems. I don't know if this is a problem of a faulty powerbook or a design problem or if there are some other solutions for it.
I bought a "Mad Dog" Aluminum hard drive enclosure at CompUSA. It came with a nifty usb power cable that works with my old usb hard drive enclosure. Only caveat is it takes both USB ports(1 to drive, 1 to power connector on enclosure) to power external hard drive but it works. I could have moved my 80 gb disk over to new enclosure but why?. I bought it on a whim and lucked out. The 2 provided cables are about 3ft long so it will reach both sides of G4.
Matjazm, You are correct in that the G4 has a 500mah limitation on usb power. Found this on another post on this board. That is why additional power cable is required. Bummer as MAC's are usually cutting edge. I hate to admit Old Intel technology works where MAC won't.