I have a brand new inspiron 580 with a 320 GB HD.  I want to add my almost new Western Digital 640GB SATA drive as a second hard drive. I cannot find any instructions for how to do this in the online documentation for this product line, or anything close that is detailed, systematic, and step by step. Is there a DIY section that I'm overlooking? The manual tells you how to open the cover and disassemble the primary drive but is silent on the issue of adding an additional one. Unless I am missing something. I've swapped drives before,  but never added a component.