i am still new at this recording deal, but here goes what i know.
It is best to use an external drive that is specially made for recording because those drives allocate space big enough for the file, instead of splitting it into many different parts like the hard drive of a computer will do. basically, the special hard drives make space to put all of the file in one spot, while computer drives scatters the information and puts peices of the file wherever it can find space. this does effect the recording quality (slightly, but it is noticeable)
Just curious, but what software are you using? i am lucky enough to be using ProTools 7 LE with a pretty nice digitech mixing board.