Hmm, that is quite the interesting situation - since I love forums I'm going to go search for an answer. :o
Edit - If you just Google rgb colors then you should find numerous sites that give you the colors and their RGB code as well as their hexadecimal codes. That is where I found this color - it's hexidecimal code is: 8B0000. So to get that color you would do this..
[color =#8B0000]TEXT[/color] (Without the space of course.)