When looking for a new flat-panel monitor, one of the most important things to consider is the dead-pixel policy held by each company. These policies usually vary widely, so it's worth doing some research. Or you could have the folks at Tested do the legwork for you with this article, which explains the rules popular LCD makers use to judge dead pixels and other display anomalies.
Apple ranks among the best in the industry with zero tolerance for any sub-standard pixels on its iPod and iPhone screens. The Mac maker is also more willing than most to replace a display with only a few problems, although if the replacement also exhibits defects yet remains within spec, don't expect a second one. HP stands tall behind its monitors, too. You can swap a screen if so much as one pixel dies completely, and six or more defective sub-pixels qualifies a display for replacement.
Not all vendors are so generous. Dell holds the opinion that it takes at least six dead pixels to earn a replacement, although its premium monitors are covered by an additional guarantee. That premium pact entitles you to a new monitor if even one of your display's sub-pixels is stuck bright. HP also holds some of its more expensive displays to a higher standard than more mainstream models.
Reading the article, I'm amazed at that wide range of standards used by the major display vendors. Life certainly would be simpler for consumers if there were one universally accepted definition of a "bad" panel.