[iBook] USB vs firewire

[ibooklist2 at matthurst.fastmail.fm]

I'm planning to buy an external DVD writer to plug into my 2 year old
iBook (with Tiger). I've already got an external HD running off it on
the firewire slot. Is my best bet to daisy chain the DVD drive off the
external HD? Or run the DVD drive from a USB port (USB only DVD writers
are cheaper too...)?

And what's the speed difference like between USB and Firewire? It's not
going to get heavy use so I'm not looking for Olympic stylee
performance, necessarily.

Anyone have any tips on prices or suppliers? I'm in the UK.

cheers

Matt