How can you check for available memory in PPC during startup

Hi,
Any body have an idea how to do this? My new game uses quite a bit of memory, so I want to check that the PPC has enough memory free before letting it run, otherwise I can display a nice message saying, please free up some memory before loading the game.
Help please!!
thanks
jake p.
Any body have an idea how to do this? My new game uses quite a bit of memory, so I want to check that the PPC has enough memory free before letting it run, otherwise I can display a nice message saying, please free up some memory before loading the game.
Help please!!

thanks
jake p.