Hi, used a few of these, the problem that you have is that a USB port can only supply about 500mA (per port), fot most devices this is adequate, but for external drives there are some that need two ports, they are then wired in Parallel to give 1000mA (1A), so if you are only using one it has the correct voltage but not enough power to overcome the initial resistance to start the drive spinning.
The standard (non mains powered) USB hubs are fine for connecting small devices (webcam, FlashDrive etc) together as the current draw on them is minimal. and a device will only draw the power it needs.
Although the two leads on your drive are labelled power/data and power this wont matter when you plug them into a mains powered USB hub, the wiring is such that it makes no difference which USB socket you plug them into, that is the basis of USB.
We have a similar thing going on at the moment with people who want USB adapters for their iPads. The USB cables are all the same, but the adapter (either car or mains to USB) are usually only kicking out 500-800mA, which is enough to power an iPod or an iPhone but not an iPad. I've seen people on eBay selling "high power" adapters which put out 1000mA, but again this isn't enough (I know, I've tried them), you need 1200mA (1.2A) for it to work, and these adapters, although they look identical, cost a few pence more to make, so upto now everyone has always made the cheaper ones. (Check if you're buying)
If you want to test this just connect an iPad to you computer, it'll sync and you can write to it, but it wont charge.
Just in case I've wandered off too much: Single USB wont do it, you need two, if you only have a standard 1-4 hub that wont do it (you're still only using one socket). A mains powered USB hub is what you need, it'll be fine and it won't damage the drive.