You can sub the 3.5 7200 drives with either SSD or drives w/ either 10 or 15k rpm (http://www.newegg.com/Product/Product.aspx?Item=N82E16822236243). You can also go with 3 and 4 terabyte 7200 hard drives as well (http://www.newegg.com/Product/Product.aspx?Item=N82E16822145562). With that said, I...