I take it you have a computer with Windows on it now or you wouldn't be asking which *nix to start out with. My suggestion is to learn Windows or whatever your current OS is. Then once you have mastered it move on to *nix. Learning how your current OS works will help you in learning a new one. Oh and if you are deadset on learning *nix I suggest using Mandrake. It is easy to install and will help you to learn basic commands and when you get familiar with it, it will help you whenever you switch to Slackware or the like.