As Safety Merv's daughter (he's the one who installed safety belts in our van before they were factory installed), I would just like to mention two things.
1. An article at CNN.com about booster seats that may not protect your child in a crash.
2. Children under 12 and/or 100 pounds need to be in the back seat. On the way to school we witnessed a car crash. Everyone was ok, but the little girl in the front seat hit the windshield because safety belts in the front are made for adults, not little kids. The child in the back seat was fine.