The beep VI doesn't use the PC speaker unless a sound card is not installed (it calls the Windows MessageBeep function (http://msdn.microsoft.com/library/default.asp?url=/library/en-us/debug/base/messagebeep.asp). If you want to use the PC speaker you should call the beep function (http://msdn.microsoft.com/library/default.asp?url=/library/en-us/debug/base/beep.asp) with a Call Library Function node. There is a KB on this at http://digital.ni.com/public.nsf/websearch/CD1557276420321D86256CA300792571?OpenDocument
Regards, Ryan K.
