Usually the keys are encoded and stored in the registry it decodes it and also allows You to change Windows XP, 2003, and .Net Product Keys just press of a button. It is simple and easy to use.

This Version has:
Supports Windows 98, 2000, XP, Vista, 7 and more - 32 bit
Supports Windows XP, Vista, 7 64 bit versions
Supports MS Office 2000, XP, 2003, 2007, and 2010 - 32 bit and 64 bit
Many Enhanced features

v1.73 has the following new addition/support:
Support for Windows 7 OS
Support for x64 Bit Operating system
Support for MS Office 2007, 2010 Beta
Removed Backup Activation and restore
Removed many bugs which are too many to mention here

Home Page - http://www.winkeyfinder.com/