The windows "Registry" is explained as follows:
In computing, the Windows registry is a database which stores settings and options for the operating system for Microsoft Windows 32-bit versions, 64-bit versions and Windows Mobile. It contains information and settings for all the hardware, operating system software, most non-operating system software, users, and preferences of the PC and so on. Whenever a user makes changes to "Control Panel" settings, or file associations, system policies, or installed software, the changes are reflected and stored in the registry.
The Windows Registry was introduced to tidy up the profusion of per-program INI files that had previously been used to store configuration settings for Windows programs. These files tended to be scattered all over the system, which made them difficult to track.
This is a VERY important part of your system. If you are not sure of what it is you are doing..DON'T touch it. Messing up this area of your system can do serious damage.
If you are the adventurous type however, then please MAKE A BACKUP before you mess with it. Just my two cents :)