How long a drive is this? I don't want to arrive at CDG, take a train the wrong direction into Paris to catch a train!
Alison,
Think about what you're going to do with that car when you're done. It'll cost you a small fortune to drop it in another country. Also, if it's only a one-day rental, the daily rate is going to be steep.
I'm not a train person, but I'd think you'd find that the trains out of Paris Nord to Brugge are very frequent and take less than three hours. Also, the RER from CDG goes right into Paris Nord, taking maybe forty-five minutes to get there. The transfer would be simple.
Edit: "Samuel" has ammended his post which previously did not address trains.
The fastest and easiest way is not the most direct one. The direct drive from CDG via French freeway A1 via Lille and Kortrik is 2 hours and 40 minutes. The drive via Calais and then along the Belgium coastal freeway is just 2 hours and 20 minutes. Make sure you do stop at the Belgian coast as it's really beautiful. Personally I recommend De Panne, Koksijde and Oostende.
By the way, Brugge is a city where a car is far more of a hassle than a benefit. Take the train. Plus, do you really want to battle Belgian traffic, which can be nasty, while fighting jet lag and travel fatigue at the same time?
Direct TGVs from CDG to Brussels depart at 07:47, 10:10, 12:35, 16:39, and 17:40. There are frequent IC trains from Brussels to Brugge.
You also can take a TGV to Lille and RE and IC trains from there to Brugge. However, you have to walk from the Lille Europe station to the Lille Flandres station and for most departure times you also have to make a connection in Kortrijk. Direct TGVs from CDG to Lille Europe depart at 08:47, 09:18, 11:36, 12:42, 13:24, and 15:25.