It is also possible to add different images to IE6 if you are displaying your images as background-images. (They should do if they are design).
Example:
Code:
#header {
lots of code: bla bla;
background: url('url_to_bg.png') no-repeat top left #ffffff !important;
background: url('url_to_ie6_bg.png') no-repeat top left #ffffff;
}
FX, Opera and IE6 (which all can handle png well) are using the first line, but ie6 dosent understand it, and jumps down to the second line. Just save the Ie6 images as jpg or gif. Ie6 users dosen't deserve good quality anyways..
Note that you may also use the underscore hack.
Code:
background: url('') ;
_background url('') ;
The last line of code will be ignored by propper browsers, but IE6 will take it.
Good luck