how does one replace notgenuine Vista64 with purchased key/ID?

I bought a pc secondhand and unbeknownst to me it had a not-genuine un-keyed Vista64Business installed. This has now expired.

I have purchased a brand new 64bitBusiness dvd with key.
How do I replace the pc's existing installation, WITHOUT doing full wipe/clean install?

I have spent months creating perfect settings, environs, etc, and simply need to replace the basic OS's info with this new productID and Key.

Any thoughts?!

Northlon25

See this tutorial:http://www.vistax64.com/tutorials/121866-reduced-functionality-mode.html
enter key which you purchased and nothing more- should work