What are ProductCode, PackageCode, & UpgradeCode ?

I've been handed a new version of a product & noticed that it has different ProductCode, PackageCode, UpgradeCode than an older version.

My spider-sense tingles and says that this may fail to update our app properly when we are ready to distribute our app (there are pre-existing installations).

Anyone has any insight on how the ProductCode, PackageCode, UpgradeCode interact with an older installtion of an app?

UpgradeCode should remain constant throughout the lifetime of your application - that is how the installer knows if you are installing a newer version or not. ProductCode and PackageCode will vary with different versions and packages.

See: http://msdn.microsoft.com/library/default.asp?url=/library/en-us/msi/setup/upgradecode.asp

Thank you Chris. You've just save me a lot of headaches and yelling, and possibly me crying.