Can you not just go to the energy saver preferences and un-check the box at the bottom of the window that says: "put the hard disk(s) to sleep when possible." ? Or have you done that already? Other than that I used to use a shareware program called "spindown fix" that wouldn't allow any internal or external hard drives to go to sleep. I used it in Panther but I don't know if it's okay to use in Tiger. Google "Spindown Fix" and it should come up.