Forget that "create a floppy" stuff - it was always an option, not a requirement.
Spitoon is basically right: a machine might not be visible unless it has one or more Shares created, a directory with the files on it that you want to share. On XP or Vista, doing that also opens up the required ports on the firewall, so you should not need to do anything more than that.
Hint: if you want a share to be invisible to others browsing the network, end the share name with a dollar sign e.g. private$. Others will only be able to open it if they know that name - but you'd still need to set the appropriate security on it.