Seems, you have the same issue as me. The windows message is incorrect. The problem is that the new Evernote installer needs the old one in order to correctly uninstall the previous version. It searches for the old installer where it was upon installing.
This is an Evernote Update BUG: it downloads the update msi file into a temporary folder, and installs it from there. The installer does not save itself to a safe place either. This means, when you want to uninstall or update, chances are that the file won't be there. It is then impossible to uninstall evernote from the Windows control panel too.
1) Don't use a temporary folder for long-term storage of the msi file
2) Please tell us where we can find the previous installers on the web, else I remain stuck with 6.7.5
PS: I have Win7.