IE and Netscape Issues(Urgent)

Hello,
i have a javascript code written for IE and i want it to work for Netscape 7.2...
i have the code as
---------------------------------------------------------------
function doHilite()  {
        var e = window.event.srcElement;
        if (e.className == "tun") {
          e.className = "tover";
        }
        else if (e.className == "tover") {
            e.className = "tun";
        }
        else if (e.className == "ph1") {
            e.className = "pover1";
        }
        else if (e.className == "ph2") {
            e.className = "pover2";
        }
        else if (e.className == "pover1") {
            e.className = "ph1";
        }
        else if (e.className == "pover2") {
            e.className = "ph2";
        }

        window.event.cancelBubble = true;
      }

      //changes the style of the selected tab to unselected and hide its text, then
      //set the style of the tab that was clicked on to selected and show its text
      function changeTab(eRow)  {
        var tabs = eRow.cells;
        for (var i = 0; i < tabs.length; i++) {
          var oldTab = tabs[i];
          if (oldTab.className == "tsel") {
            break;
          }
        }
        oldTab.className = "tun";
        var oldContent = getAssociated(oldTab);
        oldContent.style.display = "none";

        var newTab = window.event.srcElement;
        newTab.className ="tsel";
        var newContent = getAssociated(newTab);
        newContent.style.display = "block";

        window.event.cancelBubble = true;
      }

      //hide or show the text assoicated with the heading that was clicked
      function hideShowGroup(e)  {
        var theGroup = e.children[0];
        if (theGroup.style.display == "none") {
          theGroup.style.display="block";
        }
        else {
          theGroup.style.display="none";
        }

        window.event.cancelBubble = true;
      }

      //returns the name of the element containing the text associated with each tab
      function getAssociated(e) {
        if (e.tagName == "TD") {
          switch (e.id) {
            case "DescTab":
              return (Description);
            case "SpatialTab":
              return (Spatial);
            case "AttribTab":
              return (Attributes);
          }
        }
      }

      //centers the thumbnail
      function position() {
        var e;
        e = document.all("thumbnail");
        if (e != null) {
          b = document.body;
          w1 = b.clientWidth - 80;
          w2 = w1 - thumbnail.width;
          var margin = Math.floor(w2 * .5);
          thumbnail.style.visibility = "hidden";
          thumbnail.style.marginLeft = margin;
          thumbnail.style.visibility = "visible";
        }
      }
-------------------------------------------------------------------This is related to event programming. as i am not aware of events in netscape,could u help to change this bit of piece of code to work for netscape.what are the changes to be made???
help me out...

Regards