Getting music from Lacie to Ipod

Hi there I have I book G4 and as usual I had not enought space on it so I went out and purchased a LaCie Rugged All Terrain Hard disc drive to store my music and that allowed me to free up space on mI book G4. I want to update my ipod with new music purchases in i tunes as well as keeping my original music on my i pod. I seems to me as if I have to restore the Music from the Lacie on to the Ibook and then Sync. Is there an easier way? As it takes for ages to put the infomation back to the Ibook. I there a way of Making the Lacie like my hard drive that when I sync my ipod it will sync Lacie as well as the music on my hard disc on my i book?. what i am currently doing is dragging and dropping my name back for the Lacie to the hard disc drive and then syncing it to my ipod . I hope there is a better way to do this. Can you help thanks.