[Tutor] How to run two os.system commands simultaneously

[pedro]

Hi, I have two computationally intensive commands that I would like to 
render simultaneously on two fifferent computers. When I run these two 
commands,

os.system(theTerminalCommandMacPro4)
os.system(theTerminalCommandMacPro1)


the second command doesn't begin until the first command has finished 
rendering. Is there a way to send them both off at the same time?
Pete