I was wondering how to format a hard drive. Do I need to reinstall Windows ?
Before begin to format the partion or hard drive, do backup the data available from the local hard drive.
In the Windows, to format the partition or hard drive:
1. Right click on the partition or hard drive icon that you want to format.
2. Select "Format".
3. Select the File System. "NTFS" file system is recommended for Windows XP and above.
4. Click "Start" to begin the formating.
5. After the formating, the partition or hard drive is clean from any operating system. You will need to install the Windows operating system.
May be this article can help you
or see this article on eHow, http://www.ehow.com/how_2247047_format-computer-via-dos.html
Please specify which version of Windows you are using.
In any case, you cannot format the hard drive or rather the partition Windows is installed on. For that you would have to reinstall Windows. However, you can format a second partition of your main hard drive or other hard drives connected to your computer, e.g. an external hard drive.