yep, what he said, about an hour or so to swop over .... about £17 for the tank if i remember rightly, it's the little white tank below your ignition key ..
ta - whats best way to check it before I replace? Or is it pretty obvious once the tank is off?
you need to run the bike til it gets very hot, then with a torch you'll normally see water dribbling out and onyo the rad / v piece / floor etc .. it's usually a tiny hole ....