Ah, now Douglas Adams I
do know about!...
There was a series by the bbc that ran in the eighties staring Simon Jones and David Dixon as arthur and ford (respectively). The show followed on from the largely popular bbc radio show (adaptations of the first two books) and a few of the cast crossed over with it. The new film stars Martin Henderson (of the bbc's 'the office') and Mos Def in the two lead roles. The original cast of the radio show have also just recorded an all new dramatisation of life the universe and everything (or tertiary phase as it's called, to follow on from the primary and secondary phase titles that the first two shows were given).
If you hunt around the net there are loads of concept drawings and video clips (including one of the all new {!!!} Marvin suit being tested) http://hitchhikers.movies.go.com/ is an excellent place to start.
Just my tuppence
Rob