From the entire assortment of monitors we tested, the SDM-M51D is the only one to offer solely the DVI interface. It's also the only one that offers a response time of 50 ms. In fact, this monitor is from an older generation than its rivals (Belinea 10 15 35, Eizo L365, ProphetView 720, etc.) - it was introduced at the beginning of 2001. The playing field is rather uneven for it, since these younger and sprier displays are generally faster than 45 ms.
That said, its remaining specifications are good enough to keep up with the youngest whippersnapper of the bunch. Its brightness, contrast and viewing angles are equivalent to current averages. Furthermore, you might prefer this display for the same reason as you might like the Hercules - its snazzy design. The LG panel is very thin and the base attached to it is adjustable in both height and angle. The M51D also has a pair of speakers that will probably not be used except in an office setting.
The test results were pretty predictable - the M51D has a very long response time. Its afterglow is a real problem, not only in gaming situations but also in Internet and office applications. Scrolling through a document causes most of the characters to blur heavily, rendering them illegible.
Moving on to the color performance, the SDM-M51's contrast ratio of 300:1 gives it the boost it needs to display colors very well. The most pleasant settings were 70 for the contrast and 50 for the brightness. However, the M51D still has difficulties displaying shades at either end of the spectrum (lights and darks). When playing games that rely heavily on dark colors, you'll have to set the contrast to 100. In return, of course, you'll lose some of the differentiation among the lighter hues. With these settings, returning to Windows is a jarring experience, to say the least - glaring might be more accurate. You need to return to the original settings, 70 and 50.
In a nutshell, the SDM-M51D isn't exactly a gamer's dream come true.
By the way, in 2002, Sony is planning to launch a new product line, the "S" series, which is marketed as a lower-end line.
One last thing: the M51D only comes with one DVI interface, but the cable has an analog input and a digital output. So if you own a graphics card with a digital output, you'll soon be in the market for a DVI-DVI cable.