Depending what hard drive you have each drive manufacturer has their own flavors of utilities like this. I have Seagate hard drives and someone suggested to me to go to the Seagate website and download the SeaTools ISO and create a Bootable CD and use this utility to format the drive and not the Windows 7 format command. I have heard that Windows' format command still leaves a 'residue' of the old install of Windows on the hard drive even though you think you have 'formatted' the drive. But DO NOT delete that mini 100mb partition that Windows 7 initially creates or you will have potential problems down the road. There is a way under the Windows 7 setup to extend the partition to maximize the full hard drive. A system partition, which is only a 100MB and the rest of the drive for your drive 'C'.
When you reinstalled Windows 7 was it a CLEAN install? (Meaning formatted the HD with Windows 7 and had it create the partitions?) If yes, then Windows 7 (retail anyway) creates TWO partitions initially.
