how can i take a quality output of a gif file in photoshop?

I am making a .gif file in Photoshop CS5. While saving this animation, I used the steps = File > Save for web & devices > Preset= GIF 128 No Dithered Bicubic> GIF > Save. After saving the .gif file the quality of the file is gone , i get the quality out put for the same file as .png and .jpg, please help it's urgent