After using PC for fourteen years, I've switched to Mac. Mac OS really rulez, while the screen of the new 20" iMac Aluminum really sucks - it's one of the cheapest TN panel you can find these days - low viewing angles, washed out colors and lacking contrast. Meanwhile, the glossy screen somewhat compensates it's bad features. The feeling, compared with matte screen, is like someone just wiped off the dust from it - it's so clear! Ideal monitor for a designer should always be S-PVA / *S-IPS with a glossy screen and as small pixel size as possible. I'm not sure at the moment about the Apple 23" 1920x1200 screen, but when it was a glossy one, it's a perfect choice today.
It's the lowest quality LCD you can find today. First (cheapest) is the TN (film) panel, then comes the PVA (by samsung), S-PVA (samsung), then comes the IPS familiy (S-IPS, AS-IPS) developed by LG Philips, and then come the special panels manufactured by NEC, Eizo, LaCie and other high tech brands.. Coming from a super-duper S-PVA matrix to TN is a horrible horrible feeling, and I keep telling myself that the look and feel of mac and the advantages of OS X is worth it. Anyway, if it hurts too much one fine day, there's a very fine (s-ips) Apple screen available separately (yay, the price is just not right at the moment
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By the way some of the iMac-s made 2006/2007 were using s-ips panels, so there are thousands of lucky people out there having a quiet, quality computer at their desks, which also shows stunning picture. Why am I telling about this tech stuff? Because I work as a designer and photographer and a good monitor should always be #1 in the list.. By the way the new iMac has glossy screen, which is a rare rare find today - only Nec WGX2 Pro has it in the pro class these days (not 100% sure though, as samsung already have tons of models out there..)
To summarize, the cheap TN panel is a stupid annoying (but profitable) trick made by Apple. Dell made the same some years ago with the 2005(w)FP panel - they were first announcing the super S-IPS panels, then quietly replaced them with a cheaper (s)pva ones. While the s-pva and s-ips are both quite good, the TN is awful awful awful compared with them.. so apple decided to go this way this time.. anyway the future of Mac seems to be bright, as it finally (for many years actually) has intel chipsets and CPU-s.. and the design and quaity of mac is also by far best of anything you can find.