I think it might depend on what version you have Ed and what you want to update to. Someone else said that theirs was on CD but my 2006 version is on DVD.
Pretty sure mine's the 2006 version (def DVD), but will have to check for certain tomorrow. I want the most recent version as there are lots of new major roads near me.
Cheers Flynn, funnilly enough I'd got that in my watch list already, but thought there may be 'easier' ways of getting a copy! Will have to do some more digging.