Okay, I just bought Conquests today, was really looking forward to it, but when I try and play it, it closes due to an error in both IFC23.DLL in the Civilization Conquests folder, and Play the World's IFC23.DLL

I reinstalled, re-reinstalled, restarted several times, deleted the files (which didn't help, because then I get an error saying the files aren't there). Can someone help me, or do i have to return the game?

Do you get this error message: "This application has failed to start because ifc23.dll was not found. Re-installing the application may fix this problem."?

Nope. It says that IFC23.DLL has caused the error, and that civ3conquests will now close.

If you read my note, uninstalling then installing again, and reinstalling, both of which I tried twice, do not work.

Try the tech support forums. Since it's only happening to you, there may be a problem elsewhere. Not a bug.