Ultimately, we agree with the Imaging Science Foundation (ISF), a group that consults for home-theater manufacturers and trains professional video calibrators, when it says that the most important aspect of picture quality is contrast ratio, the second-most important is color saturation, and the third is color accuracy. Though resolution may be the most talked-about spec these days, it comes in fourth on the ISF list, and after you sit watching five TVs lined up side by side, you understand why. The fact is a relatively pristine high-def source such as Mission: Impossible III looks sharp on just about any HDTV, and your eye, when looking for differences, is drawn first to things like depth of detail in shadowy material (black levels) and the color of the actors' skin tone and how natural it looks.
So when buying a TV, the last thing you probably want to do is agonize over its native resolution. If you don't mind spending the extra dough for 1080p, go for it. But if it's stretching your budget, then take a pass, knowing it's not all that it's cracked up to be.