You don't need that mess to address IE6 or IE7, just use this
.classfix {
*padding: 0px;
*margin: 0px;
}
in your css, and only IE6 and IE7 will apply the styles that have an asterix before them.
I'd also suggest you validate the mark up at w3.org, if the code isn't valid it won't matter how many hacks or alternate style sheets you use, the html needs to have the correct dtd in order for a browser to know how to render the document, and the w3 validator makes sure your code complies with the rules the dtd implies. A wrong dtd and/or invalid code will always break layouts in IE6 or 7.