Ian F, this is not quite correct. The trip Beauvais-Paris will sure take longer, depending on the time of the day too.May come up to 1.30', 2.00 hours on rush hour. Consider that from CDG you also have the option of the RER (underground) that takes you into central paris in less than 30' and for 5£. The Air France coaches do the CDG-central Paris trip in 45'-1.00 for 6£.
Orly is even closer to central Paris.