If you are interested in learning more in depth about RGB and color workflow, I have two good resources for you. The first is posted on photoshopessentials.com titled RGB Color and Color Channels Explained. The article breaks down how Photoshop ‘sees’ color and translates each color in to a number equivalent that represents what our eye perceives as red, blue, or green.
The second is a new self help guide released from Adobe that details the best color workflow in all the new Creative Suite 3 softwares. Kind of a long read, you might want to jump to page 21 if you only use Photoshop. [Via]
These articles should give you a better understanding of how color is created in Photoshop and how to get the best output from your files.