In CS3, go to
Image>Adjustments>black and white> and move the red and yellow sliders around until you get something you like.
Then, maybe go to Image>Adjustment>Selective Colors> look for the White, Neutral, Black sliders and move them around again 'til you get something you like. I selected out only the middle of the flower and just selected a hint of the first color I came to using White...
Clear as mud? I guess I'm just saying "experiment, experiment!"