string and document.lastModified in status bar

I want to have "Site Last Updated" and then the date and time, in the status bar. I tried the following:

<script language="JavaScript">
var stuff="Site Last Updated "
document.write('+stuff+'document.lastModified)
</script>

it didn't work. Can some1 please tell me what to do. It would really help if some1 could give me the code. Thx alot.

<script>
window.status = "Site Last Updated " + document.lastModified;
</script>