Your computer should handle big renders well enough. Keep your hard drive defraged often and you shouldnt have to many problums unless you have a small amount of hard drive space. Your render is pretty good but Me personaly I would try to get more detail from the skin , The lights can be played with some more to help this . What program do are you going to use to scale down your renders with ? If you use adobe then you sould shrink it minus 200kb at a time. Save your renders as a BMP or TIFF or you will get even more loss when you shrink it down.