Career in civil services and in Armed forces differ as much as their preparation and selection criteria.In order to join navy u have to qualify Issb tests and interview,while for selecton in civil services require lengthy and cumbersome competitive examination comprising of twelve papers.Only psychological tests of civil services relate in some way or other with psychoogical test at Issb.Thus I think u can easily opt for both choices.But dear selection procedure of Armed forces is much speedy in comparison with selection procedure of civil services.If u get selected in Navy it will be much earler than march,2010 when C-E 2010 will take place.Therefore u would not be able to take C-E 2010.But still my suggestion to u would be to apply for Navy and see whether u get selected or not.But u should at least apply and take drastic decision only when u qualify Issb between Css and career in Navy.CHEERS