some other unit to pixel, only for IE6,IE 7

toPixel.js

// http://erik.eae.net/archives/2007/07/27/18.54.15/#comment-102291
var PIXEL = /^\d+(px)?$/i;
function getPixelValue(element, value) {
    if (PIXEL.test(value)) {
        return parseInt(value);
    }
    var style = element.style.left;
    var runtimeStyle = element.runtimeStyle.left;
    element.runtimeStyle.left = element.currentStyle.left;
    element.style.left = value || 0;
    value = element.style.pixelLeft;
    element.style.left = style;
    element.runtimeStyle.left = runtimeStyle;
    return value;
};