Besides what Jay said, regrade your lot so it will drain and do something quick even if it is a sump pump. Lots of people have sump pumps.
Your heat ducts will rust and you probably have mold and mildew. They can cause all kinds of illnesses detrimental to you and your family. Anyone have asthma, other respiratory problems, numerous and unexplained colds, sinus trouble, and allergy attacks?
Once mold and mildew get into a house, you may be looking a replacing the infected areas. Local news recently ran a story on a house where it got into the floors and walls and replacement was the only option and everyone in the house was sick all the time with numerous doctor bills. A young girl slept in bed with her head just inches from a wall that was full of mold and mildew breathing that stuff all the time. The health department closed the house because of it. The spores put off in your heat ducts will be spread throughout the house.