When Internet was not common it was hard for software programmers to validate to find if the software he built was not used without a payment. In order to do this many a times the software was bounded to the Hard Drive Volume Serial Number. But there was on glitch in this.
As a fact every time you format hard drive, it generates a new volume serial number and after that if you try to restore the backed up partition, the soft wares which had used the old drive serial number break. Moreover if the software has used your volume number to validate the key it becomes a problem too.
Hard Disk Serial number changes is one software that can upate the serial number of your formatted hard drive to old one if you have it noted down before. It Works with Windows server 2008, Windows Vista and Windows 7 and NTFS, FAT, and FAT32 File system.
So you can have this handy and if you are planning to format and still keep your software working as it is. No format required and all you need is to reboot. Download Hard Disk Serial number changer