CSS, templates and more IE frustrations

So I've recently kicked off a massive effort to rewrite all of my various websites, and yes, some blog templates, to use CSS positioning instead of tables for the layout, and XHTML 1.0 Strict syntax. I already finished one part of my personal website, with near-success. Typically, IE for both Mac OS and Windows does not display it properly, or at least, does not display it like all the other standards-compliant browsers. It could be that it's wrong, or that it's just stricter than the other browsers. I'm leaning towards wrong: I've got an element that has a higher z-index than the rest of the page inside a fixed-height div, and which has both its and its parent's overflow properties set to visible. So if its content exceeds the fixed height of its parent, the element should still be fully visible, floating over its parent element, right? That's how Firefox, Mozilla, Netscape and Safari render it. But not IE, oh no. IE cuts off the element where the parent div ends. Just lovely. Did I say "AARRRGGHHH" already? No? Well, AARRRGGHHH. Thank you.