How do I save a high quality graphic, as a gif without the graininess? I would also love to know exact settings too. ;);)

This is what I came up with in Photoshop CS3 Portable: http://i37.tinypic.com/hukke8.gif
Save for web
GIF 128 dithered
top right selected in 4-up

I want my graphics to have this quality:


I also have PSP7.