Page 1 of Firewire question

I am considering getting a MAC but there is one thing which is puzzling me. Firewire 400 and 800, i have never come across the 800 version before. i know its twice as fast but the question is.................. What devices support firewire 800 so i know if i need the port so i don`t waste the extra 300 quid on a port i don`t need.