png and margin errors in IE6

Here is the page in question: http://www.designbylanoue.com/gaf/nsd/logo2.html

Everything works perfect in current versions of IE, Firefox, and Safari. BUT... How can I fix the .png files transparency when they load in IE6. And the top navigation menu's margin is also messed up in IE6. Can someone please help me please???

Here is the css for the navigation:

#nav {
	background: url(images/nav_bar.png) no-repeat;
	height: 46px;
}
.menu {
	float: left;
	list-style: none;
	margin-top: 15px;
	margin-left: 20px
}
.menu li {
	float: left;
}
.menu a {
	float: left;
	margin-right: 34px;
	display: block;
	text-indent: -4000px;
}

THANKS