If this is just a proof of concept ignore my comment below
If this is to start creating configuration for your application a txt file will work, but is probably not the best option around there. You can use
- ini files (Please don't)
- xml files (better)
- App.config or similar (recommended, certainly if you want machine based settings)
- Database (I usually use this one as much as possible and use an app.config to point to the database)
Note that there is a difference between user settings (eg, language, application options, ...) and system settings (time outs, root paths, database connection strings, ...) You might want to split those.