Boot Screen Help

[kamasutra]

hi
I hava a big problem to make my boot screen
i saw in ThemeXP.org a some colored BS (boot screen), but BS need to have just 16 colors
my images sucks because 16 colors
anyone know how to make a cool pic and the pic stay real cool?
because if you see this link:
http://www.themexp.org/view_info.php?id=22280
isnt possible just 16 colors in this pic
ps. i just use photoshop
pls help