[jQuery] 32-bit PNG, Internet Explorer & jQuery's Animate Opacity

Hello!
I discovered two problems in jQuery work with IE 7:
1. When I try to apply animate-opacity to <div> element no effect
comes in IE 7 or 8 (but in 6 version it works!).
2. When I try to apply animate-opacity to <img> (particularly, I'm
about a 32-bit PNG with transparency) Internet Explorer (any ver.)
makes its edges ugly.
My blueprint:
$('#-div-or-img').hover(function(){
    $(this).animate({'opacity' : 0.5}, 400);},
        function(){
    $(this).animate({'opacity': 1}, 400);
});
There are no problems with Opera & FF.
As a matter of fact, my question consists in how to get over these
difficulties...
P.S. Known jQuery's ifixpng.js doesn't help as well as IE's CSS-filter
hacks.