[quote user="Robert Hook"]I would think the installer APIs would provide either a Product or Registry search capability[/quote]
Yes, they do.
[quote user="Robert Hook"]I am not sure I can be a lot of help in this area[/quote]
On the contrary: you and Yongan have both provided valuable information and insight. I have, in the past, taken a guess at installation locations and Registry details but found my guess inaccurate.
[quote user="Robert Hook"]Which installer software or toolkit are you using?[/quote]
I like Lindersoft's SetupBuilder. It's straightforward to use, and has fantastic support. I stopped using InstallShield after it arbitrarily decided my license was invalid and the company proved to be incapable of investigating, let alone solving, my problem.