If a Dopus window has the status bar visible and you are using the Vista AeroGlass transluscent border scheme, then the StatusBar appears on the bottom transluscent area of the lister, and it is difficult to read.
However if the lister is expanded to full-screen, then the border area of the lister (like any other windows) turns to black and the status bar can not be read at all (depending on Font colours selected).
Using this Vista scheme, it is not possible to change the Status Bar background colour from Settings.
Type "glass" into the filter at the bottom of the Preferences dialog and turn off the glass status bar option.
The glass status bar looks good on some background images/colours but is pretty hard to read on others. I'm not convinced it should be on by default but it's easy to turn off anyway.
If we could set the background color, then we shouldn't have to disable glass. The text clarity might also benefit from a little less of the diffusion effect.
If you set the Status Bar text color to full white and Vista Aero to Graphite, the contrast is okay. The screen grab below is with 50% color intensity. If you intensify the Aero color, it will contrast better.
Turning off the glass did the trick.