A PC monitor is the simplest and most direct route to setting up a display for your arcade machine. PC monitors provide ok quality, are relatively inexpensive and are very simple to set up. As opposed to a television or authentic arcade monitor all that is required to display games on a PC monitor is to attach the monitor to your PCs VGA connector.
One negative to consider if you are thinking of using a PC monitor in your arcade machine is that games may tend to look slightly "pixelated" (blocky looking) due to the high resolutions that modern PC monitors run at. Enabling scan-lines (black lines across the screen) can make the quality better but it still does not compare to the quality that can be achieved with a television or better yet, an arcade monitor.
It is important to note that original arcade machines were run at quite a few different resolutions and some of these resolutions will look better than others on a PC monitor. A simple PC monitor connection will never be able to give you a truly "authentic" arcade look due to these resolution issues but software tweaks and resolution adjustments can create an acceptable picture.
Fans of Vector arcade games should consider the following fact when considering PC monitors: The higher resolutions available on PC monitors create what many consider a better picture when emulating vector graphics (compared to TVs or standard arcade monitors). This is because the higher resolution (generally SXGA and higher, though XGA will do, even on a 27" CRT) makes for much smoother graphics (lines) and greater anti-aliasing. (The latter is in regard to an object or line in motion, and how continuous it appears. On raster-type monitors, due to how they draw, there is usually a perceptible watery effect.) With the high prices of Vector monitors and the Zektor Vector Generator ZVG Homepage, a PC monitor could create an inexpensive alternative to a vector machine for those willing to sacrifice a bit of authenticity for lower cost.
When you want to use a LCD monitor for your arcade, you need to think of even more things. Where a CRT monitor is multisync, it can adjust to many resolutions quite easily, with optimum scaling quality. An LCD on the other hand has a fixed resolution. Other resolutions than the native one are scaled up with anti-aliasing. Check if you like the results first. You are also limited to refresh rates. A CRT can show any refresh rate from 50-100 Hz exactly as intended. LCD screens mostly have a fixed refresh of 60Hz. A 50Hz game can look jerky when displayed on a 60 Hz LCD.
Second problem with an LCD can be the aspect ratio. Most arcades used to have 4:3 screens, wide or portrait. The biggest LCD monitor available in 4:3 aspect ratio is a 21.3 inch screen. Good thing is that these 21.3 inch screen are all high quality S-IPS or S-PVA screens with pivot options. If you want bigger, it means you have to accept the 16:10 aspect ratio. Do not try to find a big 4:3 LCD TV. They do not exist. 21 inch is the bigest 4:3 LCD TV available. These 21 inches are all low resolution 640x480 or 800x600 screens based on TN-panels with bad viewing angles and bad blacks.
Third problem is signal processing. The fastest and cheapest LCD monitors are TN-panels. They are fast, but lack good viewing angles and deep blacks (needed for Pac-Man, Asteroids etc.). Better blacks and viewing angles are delivered by so called S-IPS and S-PVA panels. But these panels are slow and tend to have ghosting with moving images. To compensate for the ghosting, S-IPS and S-PVA panels incorporate overdrive circuits to eliminate ghosting. By analizing 2 image frames, the following 3rd frame can be controlled much better. Result is a slight delay in diplaying the images from the computer. It is wise to time this delay prior to installing a LCD display in your cabinet. Run this test to see how fast the LCD monitor response is. You need a 2 head displaycard with mirrored image. One must be connected to a CRT monitor as reference, which can be expected to deliver fast response. The other is connected to the LCD screen you consider for the cabinet. Make a photo with a camera, and compare the timings on each screen. If the delay is more than 0.05 seconds, gaming will be seriously affected by the anti-ghost signal processing.