Windows is dependent on if you are using Vista or XP (or older) and you also have to create a folder with the correct user privileges. There's probably some threads about it in the Bmax forum when I was researching this before I added it to my Grey Alien Framework. Mac should be in Users/Shared/Your Game folder and it must be created with the correct privileges, again this is in my framework. This whole privileges thing is so that if a different user logs onto the computer they can read and write files to the folder (in other words play the game without it crashing). Unfortunately it's not a simple topic (took me ages to get it all right). Mind you I was doing it for a commercial game, so maybe a free game could be more lax - I don't know what sort of game you are needing it for.