Windows 7 how to format C drive

I used XP installed on the C drive, it is FAT32 format and now installed a Windows7 on the E drive. Now I want to put the C drive in Windows C, but I found it after I deleted Windows XP. I can't write it... but now I can't install Windows 7 in C. How can I ask?

There is a Windows 7 installation tool and CD-ROM installation to extract the image to the root directory of the D drive or D drive and then run the Windows 7 installation tool to restart the computer into the installation interface format C drive and then choose to install to the C drive and The CD is installed exactly the same as the tool you can send to you. //This article transferred from www.45it.com computer software and hardware application network

There is that you do not re-install the system to go to the C disk, you can not enter the Windows 7 boot file is more in the main Disk C disk DE disk number of logical disk you now choose 2, re-install the system grid C disk to install the system C disk; Second, keep the C disk to maintain the current state.