changing a stereo mix into 5.1

[gw sound]

I have completed a stereo mix for a live rock show/video and have been informed that their management wants it done in 5.1. I have been mixing for a few years now, but never in surround. I have a deadline slowly creeping up, but have been too busy to investigate 5.1 enough to jump right in. Any advice/information would be greatly appreciated. I am using 6.4 PTHD. I have also skimmed through the book and played with changing my i/o prefferences over in the session, but I am definately missing an other step. One last question- I read somewhere that some producers don't even assign any audio to the sub because most theater systems assign it themselves. Does this mean I can take the sub out of the equation?