Bax. The easiest way to install gauges is to open the Gauges folder included with the download, click Edit/Select All & paste the contents into FS9\Gauges.
There are 2 basic gauge types used in FS9. The conventional GAU files & "XML" gauges. The latter are usually configured as compressed CAB files which look just like zipfiles. This can be confusing unless you know how to recognise them. Don't unzip these CAB files or they won't work. Paste them in as they are. Open the FS9\Gauges folder to see default examples of these gauges. They will have file names like boeing747-400.cab.
PS. Just to confuse the issue, some 3rd party XML gauges are configured as folders. These will contain one or more XML files + BMP images. If you come across this type, the folder is the actual gauge so paste it into FS9\Gauges along with the others. I hope my attempt to explain it didn't complicate it even more.
