considering picking up one of the new 80GB ipods with a new machine soon. i only have a few gigs of songs, and don't really care for the whole video deal at all. but i need an another drive for on the go, something that can be powered over the firewire bus, and i want an mp3 player. but i'm concerned if the ipod is not well-suited for heavy disk use (a Photoshop scratch or final cut for example). i don't even know what rpm it runs at. better off buying a nano and a separate drive?