I've seen some complaints about not being able to Stuff things in OSX for compatibility with StuffIt 5 in classic, and I don't think it's quite accurate to believe that. For instance, I'm certain StuffIt v7, which works in OSX (PPC) makes compatible archives. The key is that you have to check the preferences and make sure it's checked for "faster" and not "better" compression. "Faster" simply means it is compressed using the older method. I could probably upload some version of StuffIt 7 but I've been holding off as I'm uncertain as to whether I really should, since it's an OSX app and still works on relatively recent computers.
