You can save LabVIEW vis for a previous version of LabVIEW but there is no option to do this for the build files from the application builder. I have sent this request as a suggestion to LabVIEW R&D and maybe this feature will be integrated into a new release but for now it looks like you will have to do the application builder configuration in LabVIEW 7.0 again. Please make sure to save your project for LabVIEW 7.0 before doing this.