I mentioned this in another thread that the external full size drives have a board in them that will do this for you, I have a Seagate external drive that I stole the 1.5 Tb drive out of and have used it to hook up other drives for external use.
I have one for the laptop drives also and it will power straight from the USB port but the Raspi will not support it directly as I can tell, but through a powered hub it should work great if the kernel can find it. (it works on a pentium4 system without problems)
I will be trying an old Xbox 360 120Gb drive that was pulled from a RROD (red ring of death) system and repartitioned it and is running on a Pentium 4 system with Ubuntu.
If you are more worried about ,spelling, punctuation or grammar you have probably already missed the point so please just move on.