I also find it really hard to lose the excess luggage I have gained from pregnancy. I'm finally starting to see results with a healthy diet (I'm on the Hormone Diet) and also regular exercise. I found that SUNTV has yoga at 11:00am, so I tried to do that Monday-Wednesday while Christian sleeps. If he is still sleeping at 11:30am then I move onto the Barefoot Dancer, which is right after yoga. I'm not a big fan of buying DVD's since I own a lot of them and all they do is collect dust.
You might also want to try some of the mommy and baby fit classes in your area. I joined Baby Salsa (great fun with the baby and great for the tummy area) and also Mommy Fit (that workout is a killer, but it has great baby time with singing at the last 30 mins of the class).
Hang in there... and keep a positive attitude. It will come off.