If all you need to do is call the exe's then the system exec.vi will do the trick. When a user selects the option from your main menu, just pass the path to the exe to system exec and it will start and run just like any other exe. The problems with starting an exe is how to pass or return parameters or stopping the exe from the main program. If you want a small main program and the ability to pass and return parameters, I would suggest you look at calling your subVIs dynamically. You can make use of VI Server and either use the Call By Reference Node or Open VI Reference. There are several examples that ship with LabVIEW that address dynamically loading and calling VIs.
