Does IE6 support css-sprites?
Yes IE 6 supports sprites but doesn't support 24 bit PNG transparency.
I use this css hack for giving IE < 7 a gif file and everything else a 24 bit png with transparency.
background-image:url(/images/sprites/icons-sprite.png);
_background-image:url(/images/sprites/icons-sprite.gif); /* IE<7 gets the crappy icons */