var curTabID = "";

//expects an <a> object with an id starting with "tab_".  the "tab_" is replaced with "tab_content_" to find the div to activate
function showTab(anchorID) {
	var curAnchor = $get(curTabID);
	var curTab = $get(curTabID.replace('tab_', 'tab_content_'));
	if (curTabID != '' && anchorID != '' && curAnchor != null & curTab != null ) {
		var newAnchor = $get(anchorID);
		var newTab = $get(anchorID.replace('tab_', 'tab_content_'));
		if (curAnchor != null && newAnchor != null && newTab != null) {
			curAnchor.className = "tab_inactive";
			newAnchor.className = "tab_active";
			curTab.style.display = 'none';
			newTab.style.display = 'block';
			curTabID = anchorID;
		}
	}
}