Computer Will Not Recognize Western Digital USB Passport Drive

I have a USB 2.0 Western Digital hard drive. It is the 120 gig model. neither of my computers will recognize the drive. These computers being a laptop and a desktop, both running XP SP2 and USB 2.0 enabled.

I did a little research and it seems some have problems with the USB ports supplying enough power to the drive. Is this the case? The reason I bought this one is that it did not require a power supply.

I think my wife stated that when the digital camera is also plugged into a USB drive the computer recognized the drive. I have not tried it, but I will take her word for it.

Any ideas?