The original is a stunning film IMO, including a surprisingly strong performance by none other than Frank Sinatra and a truly creepy turn by Angela Landsbury. IIRC the film was pulled from commercial release after JFK was assassinated, and not widely available until its re-release in the late '80s/early '90s. It's well worth a rent.
This could be a decent remake, given the cast. After the almost unbelievably awful remake of "Day of the Jackal" a few years ago, though, I'll believe it when (if?) I see it.