As I understand it, making hidden files in Mac OS x involves changing their filename to one the has '.' prefixing it via terminal. But the files I want to make hidden are an autorun.inf file and a .ico file which when placed on a usb key work to make the key icon in windows change to that of the .ico file. In windows I can make these hidden, but I want them to be hidden in both windows and mac os x. I think that if I changed the filenames to ones with a . prefix then they won't autorun in windows anymore making them useless but I don't want to give the disk to people with files sitting on the root level cluttering things up. At present they're invisible to windows users because the of the 'hidden' attribute but I'd like them also to be hidden for mac os x users.