[Samba] Problem with user ids on remote and local machines

[mike]

I have a small network with XP/linux workstations

On one Linux box there is a user which is the same as the user on the
samba server 

However when the user creates a file on the share the permissions are
not those of the user, but those of the usr_id of the user on the server
ie:

user creates file on share test.doc

user is 503 on local machine
user is 504 on remote machine

ownership is 504 504 not user

anyone any ideas