WinXP in a Win98 Workgroup

I have a win98 workgroup for file and application sharing, recently l have been forced to introduce a wipXP Pro machine onto this network.

I am unable to see the XP machine from the 98 machines or 98 from the XP machine.

Protocol in use is IP provided by a DHCP server.

Im sure that the answer is simple, and has been discuss befor, but l need a solution ugently..