Shared network drive

I have a small network of 10 computers running Professional, and my own machine running XP Pro. I want to set up a network drive that gives access to all users without asking for username or password. I did it once by right-clicking on the drive itself, and got a warning that everyone would have access. I had to reformat the drive and reinstall everything, but when I try to do the share now, it insists that everyone log in, I can’t re-create the same situation I had before (which was perfect) Any suggestions?