When you are prompted to choose where you want to install Windows, as shown in Figure G, you'll see a list of any partitions that are currently on your hard disk. As you can see in my example system there are actually four separate partitions. You may have a different combination depending on your system.
As I mentioned, performing a clean install means blowing away all existing partitions. The first partition in this list is labeled System Reserved and it was created automatically during the Windows 7 installation. A new System Reserved partition will be created by Windows 8, so you can remove existing one. The partition labeled Recovery contains the OEM recovery for Windows 7. I created the recovery DVDs soon after I got the new system. It won't do me any good going forward with Windows 8 anyway, so I will remove that partition too. The partition labeled WIN7 contains the Windows 7 installation that I am replacing, so it is definitely going. The partition labeled DATA contains all of my data that I copied to an external hard disk, so it is safe to blow that one away too.
Credit: Images by Greg Shultz for TechRepublic