Even as officials with the Service Employees International Union celebrate a big victory, they are looking ahead to further gains among state employees. State probation and parole officers have overwhelmingly voted to have the union represent them. S.E.I.U. Local 2000 President Grant Williams says the union will now try to convince other groups to get under the S.E.I.U. collective bargaining umbrella. This was the first election held since Goveror Bob Holden issued an executive order expanding the collective bargaining rights of state workers.