With a little experimentation with merging colors I have managed to update the Professional built-in palettes to generate Ribbon colors.
The Office 2007 built-in palettes for Blue, Silver and Black have a big advantage, unlike the Professional palettes, they used fixed colors. It does not matter what display settings you select they always use the same fixed values. This makes life easy as a developer. Just take a screen shot of the real Office 2007 applications and then hard code the RGB values you find using Paint Shop Pro.
Here we have the three fixed schemes.

The Professional 2003 palette is not so simple as it reacts to the display settings. So under XP it appears differently for each of the Blue, Silver and Olive themes. Without themes it acts the same way as the Professional System palette and uses the currently defined system colors.
The upshot is that you need to calculate the color used and this limits how nice I can make it look. I need to ensure the calculation gives a reasonable appearance under all possible system settings. So the algorithm ends up giving a reasonable appearance under all settings but not optimized for any one set. You can judge for yourself on the outcome with the following set of images.
Professional 2003 palette under the XP Blue (Luna) theme.

Professional System palette under XP themes

Professional System palette with the Windows Classic settings. This is how it will look under Windows 2000, Windows 2003 Server and XP/Vista with Classic display properties defined.

And just for fun this is the Slate settings.

As Office 2007 is the latest and greatest set of applications from Microsoft I would suggets most developers will use those built-in palettes. But for those supporting older machines or users that prefer other display settings, at least you know it will look reasonable.
















