Awesome understand fully now, thanks mate for your time, really helped me get to grips with it.
So Raid 0 is the most productive but has no security
Raid 1 is simply a mirror of your original drive and is simply security but wont enhance performance
Internal raid is cheapest option, keep original drive as boot drive and stripe other 2 or 3 drives as your raid via utilities
External raid is more expensive and will need a raid card but might be a bit more reliable than internal
With external raid I take sata connection is best over firewire 800?