arcgis 9.3 - How can the pixel values of a raster image be extracted under a polygon fishnet?

I have a single band raster image of 30m by 30m resolution. I have already created a polygon fishnet (grid) of 300m by 300m with point labels over that. How can I extract the mean pixel value of the raster image overlaying each feature in the fishnet grid? Is it possible with Arcgis? Please inform me.