Marquee consoles can utilize ELO touchscreens. This makes running the console much easier and is highly suggested.
Since the drivers are part of the XP Embedded build,only the ELO Touchscreens should be used. These are the same ones often used for cash registers are very durable. www.elotouch.com. Get the AccuTouch models (i.e. resistive technology which means you can use things other than your finger, like a fingernail, pen, etc.) We recommend the 3000 series.
Once you purchase your touchscreens (one or two will work), you should be able to just plug them in and boot the system (hot plugging is not suggested).
You will need to calibrate the screens. To do this, choose ELO
Touch Calibration from the 
Additional Apps button:
This dialog box will let you change various options for the touchscreens, most importantly, the calibration. To do this, use the mouse to touch the Align button. The screen should go white and you will be presented with a red target to touch. Do this with your finger from a typical viewing angle. You will repeat this two more times then choose OK to exit.
If your system does not have the ELO Touch Calibration option in Addition Apps, you will need to download and install ELO drivers from http://www.horizoncontrol.com/web/marquee/mq_download.htm.