CHARLOTTESVILLE, Va. - Republican Sen. John Warner of Virginia, one of the most authoritative voices in Congress on the military and a key figure in the debate over Iraq, said Friday he will not seek a sixth term in 2008. Warner, 80, has held the seat since 1978, when the dashing former Navy secretary campaigned alongside his wife at the time, Elizabeth Taylor. His retirement offers Democrats a valuable opportunity to challenge the GOP for the seat and possibly expand their one-vote Senate majority. "Public service is a privilege and I urge all to try to find time some time...