Find a good deal on a 19" VGA LCD, I'm gonna go out on a limb and say any reasonably mainstream brand will impress you. It will definitely be brighter and more colorful than the laptop screen. I've always thought that for text and surfing and general use, the 1280x1024 resolution on a 19" screen is ideal. Text and GUI elements seem a little small with the same resolution on a 17" panel. I like the Dell UltraSharps, with their multiple inputs and very good-quality chipsets, although we have an inexpensive Planar that is also very easy on the eyes. The Dell 30-day guarantee is nice when you're looking at LCDs with the possibilities of dead pixels, although some people will say that they've had trouble with Dell service.
You're gonna get a kick out of any affordable 19" display, they have come to a point where they are all nice and colorful. I don't consider DVI vs. VGA to be a huge deal, although the DVI input takes care of timing and positioning for you. Your iBook makes that a moot point, so don't worry about it. A VGA to DVI converter would be a waste of money, as the analog signal is just that, analog (VGA). Off-axis color shifting, or 'viewing angle', is I think the most noticeable difference between price points. I don't know about you, but I sit in front of my monitor... *smiles*
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