You should be able to simply start the first application, wire a delay (30 sec) and start the second application.
Once LV does this, it will exit itself, but since the applications are now externally controlled (you didn't close them within the vi), they should continue running.
If the applications are executables ("exe" types), then you can call (activate) the application by using the "System Exec.vi".
DLL's are a different story...
Hope this helps..
JLV