Registry key entries

In my project I want to handle for Registry entries. i.e When ever I install my product for the first time I want to write some thing into windows registry editor. and when the user starts using the software, may be in the start up form I will check for the registry entry. If the registry entry is not available I will tell the user that the software is not registered properly.
How to use the API functions for that, or is there any other way of doing that

to write to the registry use the RegCreateKeyEx and RegSetValueEx APIs or VBA.SaveSetting(s).
To read from the registry use RegOpenKey, RegQueryValue and Regclosekey or VBA.GetSetting(s).

I have a pretty good clas to read and write to Registry. Send me E-Mail and I'll send it to you with an example how to use (part of my project). My E-Mail: [email protected]
Vlad