I am only conjecturing, and I imagine someone like Nick could give a better answer, but I suppose it would be best to keep the system on one disk, samples on a firewire disk, and audio on the second hard disk. I was reading that the LaCie drives (which I own seveal of) are not as fast as some others by the way. You can buy firewire 800 enclosures and put existing drives in them - I ended up putting the second drive from my old G4 into a firewire 400 box and it works fine - plus has some cool neon lights that make the wait more enjoyable.
