running non-python progs from python

[Spiffy]

hello, i'm fairly new to python programming and programming in general, but
i have written a python prog that creates a MIDI file (.mid) and I want to
be able to play it from another prog which is written in BASIC.
It's a command-line prog that takes the MIDI filename as a parameter and
plays the file.
The 'Learning Python' book talks about using the os.system call, but I
haven't been able to get this to work.
How can I run this other program from a python script and pass the filename
as a parameter?