I have fat32 on my drive so I can take my files to work so I think it should work. I am powering both usb cables from the 2.5" drive with a powered USB 2 hub. According to HP it should work with 1 USB 2.0 cable but you need both for USB 1.0 so i think there should be adequate power. At least your post gives me some hope of a solution.

C