XP Pro with NT4 Server using Workgroup

My company has a small network using NT4 server and several Win98SE workstations using Workgroup Name (not domain) to connect the server to workstations. It’s a simple network.
Now we are upgrading the 98s to XP Pros(SP1).
I tried to set up one XPto be able to log in to the network by setting it up using the same workgroup name, I have added the new XP to the user group setup on NT4 server by assigning a login name and password, and also setup the XP to have the same login and password.
I could see and access the other Win98 pcs but could not see or access the server.
I appreciate any comment or help on this!