Drive Update Question

Hi, I am trying to update my son's Dell Precision M4600 laptop so that it will do better for his gaming. So far I have installed the the maximum memory allowed and now I am wanting to trade out his regular hard drive for an SSD drive but Ive noticed it has a slot on the side of the laptop that I believe is an express card slot so I was wondering if I could put some type of SSD in this slot as well as trading out his hard drive for an SSD drive. Is this possible and if so, what type of SSD do I need for the express card slot? Any info would be greatly appreciated! Thanks in advance!