You can use LEDs like these,
http://www.adafruit.com/products/306, from Adafruit.com. They are controlled by one wire and Adafruit has already created the libraries you need. Be careful, though. The LED controller chips are very sensitive to static and reversed voltage. If you blow one, all the LEDs after it will be dark.
We plan on using an Arduino Mega 2560 to run our graphics this year, which will include LED strips and perhaps an LED panel.
Pay a lot of attention to how you're going to trigger the graphics. With the cRIO, you can use the RS232 port, I2C, or even dedicated GPIO lines that you raise to tell the Arduino which routine to trigger.
Hope this answer helps.
Ray