I think it is a matter of personal perception as well as hardware.
I mean what you see, is not the same as what I see. Our eyes interpret colors differently based on the tristimulus value of the actual color displayed. A pale orange yellow interpreted by my brain might be a total yellow color in yours.
Next, you have the hardware itself. Not all LCD screens are created equal, nor are the CCFL tubes that brighten the background enough for us to see the colors. You've seen that yourself on two models of the same HPC, yet the screen is different looking.
Now add in the factor that there are many manufacturers of these old things. NEC's display is not exactly the same as Sigmarion or HP. Slight differences, even when displaying the same exact color based on mathematical color values.
Now add in other factors such as hue and saturation...and the differences become even more overwhelming.
The original 8 bit color palette was designed to satisfy the display needs of colors under the limitations of hardware and memory. You mentioned RDP, and you will see big differences there because most RDP interfaces reduce colors to the 256 color palette in order to conserve bandwidth.
And even if you draw a picture on your desktop, when you go to display it on your handheld, the DDI function will often map an RGB color onto the closest available color supported by the device.
So what I say is this: Make your background the way you want to see it on your handheld and to hell with how it looks anywhere else.