I was worried at first you that you wanted us to give you a recommendation for a motherboard, thankfully, you didn't.
You may add a express card:http://www.newegg.com/Product/Product.aspx?Item=N82E16839158025&cm_re=ESATA_CARD-_-39-158-025-_-Product
BUT! 3.5" HDD require external power. In this case, you need an external hard drive enclosure, which would eliminate the reason to get a eSata express card. I am not aware if the express card slot has that kind of electrical power.