I'm not sure if this was asked (I coulnd't find it), but under which filename should I save my images to achieve the best effect? I have Microsoft 2000 (my old computer) and when I insert the PDN image in PowerPoint, which is saved as .png, it comes out dotted and doesn't have that nice gradient to it. On Microsoft Vista, however, it retains that nice effect. I need this for a project and I want the best results. Suggestions?