MAybe a little late to the party... but are you wanting some form of "opaqueness" in the image (such as a drop shadow that can be partially seen through)?
If not, save the png with index transparency, as it's Alpha transparency that IE struggles with.
Alpha image filter should be able to be used in CSS files as well as in the main document as well, which means if it's part of the "design" (rather than the content), then you can slap that in.
Yeah, I'm trying to use a shadowed logo. I have tried using png8 alpha transparency which does eliminate the issue of the greyish box, but unfortunatey it is not just slightly jagged with the shadow removed as a normal image would be, it's totaly jagged to the point it is horrid. When I use this with a normal image it's usable but not with the shadow.
Didn't want to have to use a js solution, but it appears I may have to until ie6 finally gets put out of its misery and buried somewhere far far away!
Thanks heaps for the help :)