UNTIL recently flat-panel liquid crystal display monitors played the same role that credenzas once did in corporate offices: they were given only to senior managers as a sign of their status.But L.C.D. monitors are making their way down the technology hierarchy. Several manufacturers are offering flat-panel displays intended for household users at roughly $400, the same price that a conventional cathode-ray tube display fetched just a couple of years ago.The most obvious advantage to flat-panel monitors is space. Most of the lower-cost liquid crystal displays I tested were about as thick as a hardcover book, and nearly all perched on a stand the size of a dessert plate. They consumed far less desk space than the C.R.T. screen I had been using.Once turned on, they revealed that svelteness was not their only distinguishing feature. All were much brighter than any C.R.T. display or laptop L.C.D. I had ever used. Indeed, unless I made adjustments, some were almost painfully bright. Representatives of various L.C.D. screen makers whom I consulted acknowledged that the brightness of some units were set too high to boost their showroom appeal. (All of them suggested that this trick was only played by their competitors, however.)Once properly adjusted, the added brightness was welcome, particularly in rooms where a flood of sunlight made C.R.T. displays look washed out. None of the liquid crystal display panels withered when sunlight poured in.The brightness and crisp colors result from a different screen technology. C.R.T.'s are essentially dark screens that create an image by generating light. In contrast, liquid crystal displays form images by blocking light. Every pixel contains a red, green and blue filter covered by a liquid crystal shutter that can open to allow light from the display's fluorescent backlights to pass through to users' eyes.For that reason, staring at aliquid crystal display screen for hours seems to be less stressful than working with a C.R.T. -- so much less so that for many people it justifies the higher price. Because the phosphors in traditional monitors dim rapidly, their images have to be refreshed 60 or 75 times a second, depending on the screen and the computer. In flat-panel displays, the liquid crystals rearrange themselves only when the image changes, and even then, the rebuilding is much less obvious.''For me it's difficult to go back to a C.R.T. just because of the stability of the image,'' said Rey Roque, vice president for marketing in the digital information technology division of Samsung, which makes both types of screens.Most computer owners have to go through some extra fiddling to set up an L.C.D. screen. While old-style monitors need an analog wave or signal from the computer to do their job, liquid crystal displays are digital, like the computers to which they are attached. That means that most L.C.D. models on the market have special signal-processing chips that go through the convoluted routine of taking the computer's analog signal (itself originally converted from digital data) and transforming it back into digital data.That is where the trouble begins. If the screen's analog-to-digital processor and the computer's graphics processor are not synchronized, the fuzzy images might send you running to the eye doctor. The Sony SDM-M51D and the NEC MultiSync LCD1550V start their adjustment programs automatically. The Sony, in fact, doesn't even indicate what it's up to while it sorts out the image. The Sharp LL-T1501A's automatic setting, however, could only advance things from extremely blurred to slightly blurred. It took some fiddling with manual controls to negotiate a settlement between the computer and the screen's electronics.Eventually this synchronizing ritual will disappear as more computers begin offering digital monitor output. This is already the case with recent Macintosh computers so the Apple monitor has the smoothest setup of all.There were few disappointments among the screens I tried when it came to image quality. The monitors that offered the best value were 15-inch NEC units that were also the least expensive: the MultiSync LCD1530V, which sells for $399, and the MultiSync LCD1550V, which was introduced this week and sells at the same price. The 1550V is slimmer and a bit more stylish so customers may want look for it in stores unless the older model is heavily discounted.In principle, Apple's 15-inch all-digital Studio Display ($599) should offer sharper image quality because it avoids unnecessary computer processing. While it was indeed crisp, it was not obviously superior to the best of the screens that have to transform an analog signal. With its shiny, translucent design, the Apple monitor looks like it just escaped from the Clinique counter at Saks. It breaks with the industry pattern by setting up like an easel, with two edges of its screen and a hinged arm providing three-point support. Unfortunately, that arrangement requires more desktop space than the single pods of other screens, and the shiny plastic surrounding the screen creates annoying reflections.The Sony SDM-M51D ($580) was the biggest disappointment despite its attractive exterior design. The unit I borrowed had an annoying defective pixel that remained constantly lighted. It also came packed with a notice warning that the screen might have defective pixels but then stating that ''This is not a malfunction.'' The Sony screen had two tiny built-in speakers of such poor quality that they were shamed by a pair of external speakers I bought for $15.At $559, the I.B.M. T560 was not the least expensive screen I tried, but it was by far my favorite. The gymnast of the monitor world, it has a cleverly engineered base that allows the screen to be rotated 90 degrees, so that a horizontal screen can be turned into a vertical one. Two clicks on an on-screen button reorient the image. The monitor can even flip backward to display information to someone sitting on the other side of a desk.It sounds like a gimmick, but I found the T560's rotation feature to be a revelation. Some activities, like basic typing or using Microsoft Outlook, are made for a vertical screen. David Hill, the director of design for I.B.M.'s personal computing division, said that the horizontal, or ''landscape,'' display became dominant in the early days of PC's because it accommodated programming information better. The T560 give users both options, a feat that no C.R.T. monitor can easily duplicate.None of this means that C.R.T.'s are about to disappear. Paradoxically, high-end users in the graphic arts may be the last holdouts, amid a debate about the absolute accuracy of colors on the liquid crystal display screens. ''This isn't really an issue at the consumer level,'' said Christopher Connery, a manager of the L.C.D. product line at NEC. ''But for people like animators at Pixar, when it comes to full-motion color material, C.R.T.'s will have advantages over L.C.D.'s for years to come in the same way that conventional photography has advantages over digital imaging.''But for ordinary users for whom space is at a premium or who find that conventional displays tire their eyes, L.C.D.'s may finally be worth the cost.