File Sharing is enabled now what

I have three systems setup with a Linksys switch box. XP can not see WIN2000 but can ping it. 2000 can see XP fine. Neither system can see Win98 nor can i ping win98. In addition, to the above 98 can not browse the network workgroup. I have all networking configuration inplace, print file sharin ect. and I have the names unique and I also have the Workgroup name the same on all systems. Why can’t Win98 browse and why cant XP and Win2000 see 98. I need 98 on the network. HELP… Also, Whycan’t win2000 see XP.