Abstract: A method of order entry, product selection and inventory control for building products, building product accessories and building product components sold by a dealer to a customer. The method comprises the steps of providing a computer having a display screen and a plurality of files. A first file lists descriptions, dimensions and styles of available building products by product code along with building product accessories. A second file lists rough opening dimensions and building products fitting the rough opening dimensions and a third file lists building product components. A customer can enter into the computer a product code, a rough opening dimension or plural product codes for a desired building product. Based on the entry, the computer will select a building product. The computer then determines and displays the desired building product along with a price. The customer can then order the desired building product from an inventory.