I started using Pilates DVDs to exercise before I had my son who is now 18 months old. I started back up just recently for the same reason you are looking for a DVD.
I just looked for my set of DVDs and it seems my neighbor has borrowed them again so I can't get you the title, but I found them online.
I believe they are Mari Windsor Pilates. The set I have has three DVDs that gradually increase in difficulty and exercise time. The first one is 20 minute exercises and the longest is an hour and a half with Yoga intermission.
I like them because Pilates is relatively low impact but you really feel the workout! AND they focus on building your Core muscles (the tummy) which is what all us mom's can use the help on!!!
Good luck!