Set It Up
Once you have all of your hardware in hand, start by mounting the monitors to your stand. Generally you must remove the stock desktop stand from the back of the LCD panel; check the monitor's documentation for details on how to do that. Afterward, attach the new stand's mount. Some mounts are angled, so be careful to orient your display panels in the correct direction.
Attach the power cable and signal cable to each monitor before you mount them. I recommend that you use the retaining screws on the cable connectors to make sure that the cable remains firmly attached to the panel. Reaching the panels once the monitors are all mounted on the stand will be difficult at best, so you should take care of the cable connections once and for all at this point.
After you have connected the monitors, install the second graphics board in your computer, if necessary. Follow the instructions that come with the board and your PC, but first be sure to turn off your computer and unplug the power cord--even if the PC is turned off, the motherboard can still have power, which can permanently damage the graphics card when you try to install it. Also, confirm that your new board will not impede the flow of cooling air to the existing graphics card or any other expansion cards. Many have small fans on one side; don't block the fan's air.
Once you've installed your extra graphics hardware, connect the monitors. Attach the lower-left monitor to the primary connector on your first graphics board, and the lower-right one to the secondary connector on that card. Link the upper-left monitor to the primary connector on your second graphics board, and the upper-right screen to the remaining connector. This setup will make configuring the screens correctly in Windows' display manager easier.
Now turn on your computer. After it completes the boot process, you should have the Windows desktop on the lower-left monitor. In Windows Vista, right-click the Desktop and choose Personalization, then select Display Settings to open the Display Settings window.
Click the Identify Monitors button in the upper-right corner. Large numbers will appear on each of the monitors. In the window, click on the numbered icon that appears at the lower left; in most cases, this will be Monitor 1. (Some graphics boards will have their own utilities to manage multiple monitors. Check your card's documentation for this feature; alternatively, you can just use the Windows utility.)
Two items--'This is my main monitor' and 'Extend the desktop onto this monitor--should have check marks and be grayed out for this monitor. If that isn't the case, put check marks in both boxes. Make sure that the Resolution slider is at the panel's native resolution; consult the specifications in the monitor documentation to verify the native resolution. Click the Apply button.
Next, select each of the remaining monitors in turn. Set them to their native resolution using the Resolution slider, and then check Extend the desktop to this monitor. Click Apply after adjusting the settings for each monitor.
Finally, drag the icons of the monitors around so that they correspond with their physical location on the monitor stand. Once all the settings are as you want them, click the OK button to close the window.
You should now be able to open applications and put their windows on the different monitors. If the window is maximized, it will fill one monitor and you won't be able to move it. If you adjust the window to a size smaller than full screen, you can then drag the window to another monitor. Maximize the window there, and it will snap to fill the screen.