How long will it take me to go from Gare de Lyon to GareNord

I want to book a train from Vichy to Paris and then from Paris to the Hague. I don't know how long I need to plan to have time to go from Gare de lyon to Gare Nord. Can anyone tell me? How hard is it to get from the Gare de lyon to the Gare Nord?
Thank-you for your speedy replies

From Gare de Lyon, take RER (local trains) train D heading to Orry-la-Ville. The second stop is Gare du Nord, it's a 5-minute train journey. If you have an hour of time between trains, that should be more than enough.

RER tickets are on sale from a machine before you enter the station. You will need a ticket T+, which is a simple ticket.

[ Edit: Edited on 28-May-2009, at 00:54 by bentivogli ]