Actually after reading the specs of the controller on that Rosewill card you link to I do not believe it will support more than 4 hard drives.
"Rosewill special design, ?Magic Switch?, allows two modes operation.
Mode one: You can active 4 internal SATA ports and two external e-SATA is off-line.
Mode two: You can active 2 internal + 2 external SATA ports for connecting your e-SATA enclosures and SATA devices. In this mode, two internal SATA channel will be off-line."