When Coldplay sampled Kraftwerk on their third album, X&Y, it was a signifier for the British band, telegraphing their classicist good taste while signaling how they prefer the eternally hip to the truly adventurous; it was stylish window dressing for soft arena rock. Hiring Brian Eno to produce the bulk of their fourth album, Viva la Vida, is another matter entirely. Eno pushes them, not necessarily to experiment but rather to focus and refine, to not leave their comfort zone but to find some tremulous discomfort within it. In his hands, this most staid of bands looks to shake things up, albeit politely, but such good manners are so inherent to Coldplay's DNA that they remain courteous even when they experiment. With his big-budget production, Eno has a knack for amplifying an artist's personality, as he allows bands to be just as risky as they want to be -- which is quite a lot in the case of U2 and James and even Paul Simon, but not quite so much with Co