I have a suggestion for you, if you would like to try it out.
Once you get your new one in, if you have an old PSU lying around, then that is perfect.
Here are the steps, this is to make sure that everything will work ok.
Make two simple linear - only because they are easier on BOM, then you can make your own swithing or buy off eBay.
The 5v to be at least 2Amp or 3Amp, or for convinience, use the TO220 1.5A the L7805, not LM unless that is what you have, then it will be good for 1 Amp. That should be enough anyway for the usb ports, just...
Each USB channel needs at least 500mAh, as per spec or a little more, for USB rev 1.1 - 2.0.
Then also make a 3.3v.
This can be as little as 0.5A or 1A. This is due to powering the board only.
Then connect the power to the header pins.
Use the 12v from the 4 pin molex or diskette drive connector, either size molex connector will do, if going up to 2A.
More than that, use the larger Molex connector.
This way, you will know if it is the power, if it is, then you can just de-solder the onboard linear, and buy those switching ones :-) and you will also have two regulated power supplies boards ready for other experiments.
Once you get all that sorted, just add an external H.D.D. for extra storage ;-)
Another thing to check for, but now a little late, is the 5v rail on the USB. It should be between 4.75v and 5.25v, anything outside that range, and you will be having problems.
Now, as for your "powered" USB hub... have you ever checked the power supply rating for it?
I ask since most of the ones I have personally come across have a very small power adaptor ( or wall cube or whatever it is called in other parts of the world). It should be capable of at least 500mAh PER PORT.
I have seen adaptor included in packs that were 300mAh!! Much less than what the USB port actually provides...
Unless you do a design similar to what was published in Silicon Chip a few years ago... then you need to beef up your adaptor to match your hub.
p.s. I do not own yet a Pi, but I am contemplating on buying one soon in the next couple of months. Not to mention I will need to learn how to do the linux thing.