Jim Dee :
Thanks for your quick reply! I created a "Win 7 repair disk" (DVD) as advised by the software when I first booted up the computer. So are you saying that's all I need to install it on the new HD?
Usually the repair disk will only do disk repairs, not a full reinstall. Most computers now have the software to do a full install in a special partition on the hard drive, with some option in Windows to create a system restore disk in case your drive fails. Look in your Start menu for a folder with the name of your computer (Dell, for example) for the utility software to create the disks. You might also be able to call the manufacturer to ask about creating the disks, or do an internet search on the same topic. Most computers prompt you to create the disks when you first get the machine, but, of course, most people ignore the suggestion. The software to create the disks should still be there if you can find it.