Quote:
My USB ports are only 500mA each would it still work?
All USB ports are 500mA. The USB standards demands it. Actually, some ports can't even supply 500mA, it was a problem a few years ago on most laptops. Today it's not really a problem though. Some laptops have one of their ports that has trouble supplying half an amp, but the other port usually has no trouble.
As for USB hubs, it's not a clear fix. Some hubs come with a power supply that can't even power a single port at half an Amp. Sadly, most spec sheets don't tell you how many amps the default wall wart can supply. USB standards demand that every USB port must be able to supply half an amp. That means a 4 ports USB hub must have a power supply over 2 amps, and a 7 ports hub must be fed at least 3.5 amps. In practice though, it is rare that your usb hub need to supply the full half amp to everything connected to it. This is why most usb hub manufacturers don't give you a powerful enough wall wart. For example, the famous D-Link DUB-H7 comes with a 0.4 amp wall wart, which is not even enough to fully power a single usb item. The Rosewill RHUB-300, another 7 ports hub, comes with a 2 amps wall wart, which is barely enough to fully power 4 of it's ports. The GWC HU2G40 is a 4 ports hub that comes with a 2.5 amps adapter, which is perfect.
But, if you plan on powering your D7 trough a hub anyways, you might as well replace the stock wall wart with a better power supply, regardless of how many amps the default is rated for. Astrodyne has a bunch of 5v PSU rated at 2amps and up, which should be a good replacement. If you want to go overkill, you could always buy/build a linear power supply.