Wireless network – extending the range

I need to install a wireless network in a 4 story, 14,0000 sq. foot house. There is one active ethernet cable connected to cable modem on the 2nd level, middle of house. I contacted LiNKSYS Technical support 3 times asking what would be the best equipment to purchase. I received 3 different suggestions for configurations. Can anyone offer an idea of what would be a good solution providing the best range.