|Do you mean cmd's "??? is not recognized as an internal or external command" babble? If so, then you need to type the full path to csplit in cmd. For example, if it's on your desktop, then something like cmd c:\"documents and settings"\administrator\desktop\csplit|
If you mean csplit spits out the error, then /? isn't a valid command line switch for the program.
My work in progress. I hate JS. :P