Are you talking about a roaming profile - so you'd want to copy the local profile to a location on the server? You can use the copyto feature (system properties, advanced, user profiles button) on the XP machine - browse to server folder to copy to) for this.
If its just the local copy of domain profile, bcastner's given you some things to try - I'm not sure if the copyto feature would work copying the local profile over the local copy of the domain profile on the same machine.