(redirected) SSD Alienware X51

I just got my Alienware X51 with solid state drive option  (256gb SSD) + 1tb Sata. the computer says that I only have 921gb of space on the harddrive. So I wanted to know if my computer actually has the ssd that I opted for or if that is normal for a ssd + regular harddrive computer. Because wouldn't the computer have more than 920gb of space due to the ssd? Is there any way I can check if I actually have an ssd?