Yarp, slooow is correct. not sure about the 40 gig fact. my cousin can run her 80 gb samsung notebook hd on her desktop with just one usb but not mine. guess depends on how many usb device you attached to you ports and also the power the case took too.
The specification ratings of USB is at least 500mA which is much lower than the 800mA - 1A requiredd by 2.5" HDD. Most notebook's USB can produce more than 1A but some lower budget Notebook only design at 500mA. My company's Dell Latitude Notebook (Business class) can power 3 80GB HDDs at the same time without any problem. But my home Compaq Presario (Consumer class) can only power 1 HDD. My brother's older Compaq Presario can't even power 1 HDD. Have to use the 2 USB cable.