On Dell's website, it lists displays as being "WLED" or "RGBLED". What is the difference between these two types of displays?
Okay, I'll take a stab at the RGB question. The backlight of the screen used to be cold cathode type bulbs. Think super thin flourescents. The problem is that they were power hungry. The next generation used a white light LED to save on power. The problem is that there is no such animal as a white LED. The LED is actually a yellow LED with a blue coat. Sometimes that creates a slight shift in color. Slight yellow or yellow green tones are common. You display may show this shift with slightly off color images.
RGB uses pure color Red/Green/Blue LED's. When you focus them together, they create a true white light and this focused through the display should create brighter, truer colors.
White LED's are actually blue leds with a yellow phosphor, and thus creating an white impression. This technique allows a colour gamut slightly wider than sRGB, but not very "colourfull". RGB leds consist of 3 individual colour leds, red, green and blue. These allow an enourmous colour gamut that covers most standards like AdobeRGB and NTSC. Panels with RGB LED's are much more expensive, as they need much more calibration logic. It is very hard to tame extreme gamut for say sRGB use, and the ballance of the colours is constantly monitored. RGB LED displays are doing twice the price of WLED's with ease.