Software Deployment

Hi - This is most likely covered in some way somewhere, but I can't find the specifics on this:
I need to push out a patch for office Communicator 2007 to 100 users. They are all logged on and the program is currently running.
I just need to know the command line switches to install communicator.msp - and what schedule would be best? meaning
should I have it execute any time (probably not) - next boot up? - after logon? - while user logged off?
I have deployed exe files, but I am having problems with msp's..
I am a newbie and still learning how to use this tool so ANY help would be greatly appreciated!

Thank You!

Blaine