Here's an easier way to make a fake backlit display: paper on back of acrylic. First design what you want, then use good sharp knife to cut out the design and paint the rest black. Use rbber cement to mount the design on the back side, mount the fake display on your PC and add CCFL or LED behind it for lights.
Or you could hit eBay and find an LCD display for about $10-$20 and build the cable to connect the display to your PC's port, download LCD software and set it to display your desired message.