Novell Server and WinXP Login

I have a Novell 6.5 SBS with a Win XP machine using novell client 4.90 and another with 4.90 SP2. Both of these clients require the user to log in to the server. If the user has an account on the windows machine, it’s okay, but if they don’t, WinXP prompts for a windows password. How can I make the WinXP machines take the Novell login username and password regardless of who it is – as long as they are authenticated on the server?