Transparent PNGs and jQuery animate()

Transparent PNGs and jQuery animate()

I'm using superfish which uses jQuery's animate() method to fade in a submenus for my nav. The problem is my submenus have transparent pngs with a drop shadow in the background and IE isn't capable rendering two filters at the same time. That is it can't rending the animation and the png drop shadow so I get a weird flicker effect. If I just remove the animation it would fix the issue, but when I pass in a null value it gives me an error.
  1. #

            $('ul.sf-menu').superfish({
                delay:       1000,                           
                animation:   null // this give me an error
                speed:       0,
                autoArrows:  false,
                dropShadows: false
            });












any ideas?

Thanks,
a jQuery noob