anything over 2000 x 2000 btw...the higher the res, the more detail... many pros use images ~5000 pixels JUST FOR THE FACE! Years ago, when ram was limited and high price, a lot of people said not to use high res textures. It is being discovered that this practice is not correct. Images that are close up's of an object must have a high res texture..however, images that are at a distance from the camera do not need one. As stated above 512x512 would probably be ok for images that are not closeups...but as most texture magicians are now after the "close up", you find that this is very much different. The hair texture I have for the poser cat fur is a 2500 x 2500 map. Smaller will simply NOT work with it as the lines in the image file actually determine the detail and fineness of the hairs. So it depends on your target market. Do you want close ups or normal renders...