Is in RWPhotos a tool, wich reduces the colours to two colours( black and white)?
Not directly, but you can use the Grayscale filter and then increase Contrast couple of times or use the Levels filter.
Or you can save the image as BMP and set the format to 1-bit. You can also choose, whether to dither or not.
Find out how Vista icons differ from XP icons.See how RealWorld Icon Editor handles Vista icons.
