Smaller is better, but is .01 mm really noticeable? I think it can be. But on a second monitor (which rocks, been using that type of setup for over 6 years) I don't think it will matter. Unless the main monitor goes (gasp).
Many of the flatscreen CRTs are actually a variable pitch grille. Although many of today's monitors have Sony trinitron tubes, there are some subtle and not-so-subtle differences in the overall quality between brands. Some of Mitsubishi's monitors have won great praise, yet others didn't get such kind praise in the past.
Be sure to read some reviews (macworld.com, etc.) before plunking down your hard earned cash.
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-Keith
-Whatever you do, do the research.