Ummm, huh? JPEG and GIF have nothing to do with each other at that
level. The reason many still use GIF is probably threefold:
1) GIF works better for lineart and other things of limited colors and
sharp edges. JPEG works better for photographs with lots of colors and
smooth gradients.
2) GIF is older, which means there's more GIF software than JPEG software.
3) JPEG gives better quality images upon decompression in terms of number
of colors. Since many graphics displays don't support as many colors as
JPEG provides, decompression has to go thru a color-selection step too,
which can be slow.
--Darren