This is also a sort of accessibility question.
with my sites i like using .PNGs for headers and such and a lot of them are transparent, IE has a problem doing transparent PNGs (the fix didn't work for me) so should I do it all in GIFs (less quality) or take up the extra work and code two stylesheets, one for IE and one for firefox etc.
firefox having pngs and ie having gifs.
yeah so, do you reckon it's all worth the trouble?