Can not access a network system!

Hi all,
I have this network that has only one domain controller, my number one problem is how to make my win 98 workstation join the domain and be accessed by the domain controller. Again two of my workstations with winxp that are already part of the domain and can be accessed by the domain controller can not be acceseed by other workstations on the same domain. I think it has to do with security issues but not sure, how do i go about it.