CD Keys, offline registry editing - migrating to the new Windows XP install

The fresh install of Windows XP generated a few interesting questions.
How can you read / change the registry of another Windows instance?

1. The registry consists of 5 files in c:\winnt\system32\config. (see details here)
2. Copy these files over to your new instance. (If you have access to the drive, use the recovery console).
3. To read and manipulate these offline registry files, use regedit to load the 'hive' files. (see details here). You can even fix the offline registry and copy these files back to the original instance.

How can I recover my CD keys for Microsoft products (like Office XP, Visual Studio.NET, Office XP ....)?

There were a couple of programs that I found; RockXP , "Win KeyFinder 1.65" and "Office Keylight 1.00", "CD Key Finder: Magical JellyBean" . I liked RockXP. This thread discusses how these CD keys are stored in the registry.

Some other sites that I encountered along the way

PC Audit: http://www.belarc.com/free_download.html - shows all software and hardware in a nice local HTML page.

Windows IT Pro: http://www.jsifaq.com/

Registry tricks: http://www.mdgx.com/reg.htm

Free 60 day trial key for Office 2003: http://www.microsoft.com/office/trialkey

Creating a slipstream installer: http://www.jsifaq.com/SUBF/Tip2500/rh2529.htm

How to recover from a corrupted registry that prevents Windows XP from starting: http://support.microsoft.com/kb/307545