A – are you operating as a workgroup with all machines having ‘File/Print Sharing’ turned ON? And if so, WHY?
B – XP Pro w/SP2 with Firewall enabled will definitely block the other members of the workgroup from seeing the new machines.
C – If you are running the 2000 Server as a donmain controller with a network shared folder/drive, then that is all any machine in the domain should see. Operating as a workgroup puts the onus of file access control on the individual user and is a bad practice.
D – if it is necessary to make the XP systems a visible part of the workgroup and allow browsing by other members, then – Turn on File/print sharing in the network connection AND open the prots for NetBIOS and SMB in their firewalls 9primarily 135, 137, 139 and 445. Depending on the applications involved you may also need to allow some of the higher ports (i.e. 1680 SMB reply).