Recording On Pwrbookg4, firewire/latency question Options

[rosewood]

hi all,

I kind off decided to by a new powerbook g4 1.25mhz running dp4 with the motu828mkII replacing my old G4 350mhz with digi001.

Since the internal hard disk of the powerbook runs at slower speed someone adviced me to record thru firewire on an external hard drive running at 7200.
my question is ; is this really advicable and more shouldnt be there any latency of any kind when you record thru a firewirebased interface (828mk) to an external hard drive also connected thru firewire ?

Thanks in advance

Rose