Hi Loulou -

In smart art, there are two pre-set items that could work for you: "Cycle Matrix" or "Segmented Cycle". Cycle Matrix already has 4 quadrants, but if Segmented Cycle looks better for your needs, you can add another pie slice.

If neither of these will work "as is", then after you insert the one that will work best for your slide, you can convert it so you can edit the individual pieces on your own. The easiest way to do this in PowerPoint 2010 is the click on the "Convert" button on the Smart Art menu and choose to convert to shapes. Once that is done, ungroup it and then you can edit/add/remove pieces to fit your needs.

Hopefully that makes sense! Good luck!

Another way is to create 4 boxes of your colors stacked vertically, and save as a picture. Then fill in a circle using that picture. You might have to tweak a bit.