idc:
I opened a file in the hard drive which I called itunes. I then opened the file on My Computer that contained all of the itunes music files (just the music files, not anything else itunes related). I then dragged and dropped the file from My Computer to the hard drive. Depending on how many files that is it can take some time and is best done in batches.
Then I went into itunes and Edit > Preferences > Advanced tab > itunes media location box > Change > locate the new folder with your files on the hard drive and select and OK. Now your computers itunes knows where to find the music files. You obviously need to have the HD connected all the time to play.
I have a USB HD and there is no effect on SQ!
Sorry idc, but are you sure? I'd have thought this would just ensure that iTunes knew that new files were on the hard drive, but that it still plays the old ones from your existing hard drive? i was going to say to change your media location as you state above, but then do a 'consolidate library', which moves all the existing content into the new location?