File sharing is a whole new ballpark.
Win98 may have trouble reading long folder names, resulting in your w2k shared folders not appearing to w98 users. It has to do with the length of the folder name. W2k has an option where you can set a name for the shared folder without chaning the name of the folder on your w2k system.
You also need to create user accounts for EACH user that logs in, unless you are running a server/client network as opposed to a peer-to-peer network.