Hello everyone I have recently built a new computer from basically scratch. The only things I am transplanting from an older rig are a 2tb hard drive and a power supply. I do have one question though before I buy a new OS for the new rig. I knows since I am transplanting the hard rive I need a new OS and cant use the one that came factory installed on my older Dell rig so I am looking into getting Win 7 because I have always been fond of it over other microsoft operating systems. Since I already have windows 7 installed on the HDD I was wondering if I use a refurbished OS such as "Windows 7 Home Premium SP1 64bit, System Builder OEM DVD 1 Pack (For Refurbished PC Installation)" will work. People say in the reviews that its not intended for a clean reformat but works well on a rig or HDD that has already had Win 7 on it. Or if I should just pay a bit extra for "Microsoft Windows 7 Home Premium SP1 64-Bit DVD + Genuine Product Key". I have also seen products that offer a registration key and digital download through e-mail. I am not sure what will be best for a HDD that has been transplanted into a new rig. Thanks