I found this script and it appears to work great in both Internet Explorer and Firefox.

Code:
// Clock Script Generated By Maxx Blade's Clock v2.0d
// http://www.maxxblade.co.uk/clock
function timeSource(){
   x=new Date();
   x.setTime(x.getTime());
   return x;
}
function leadingZero(x){
   return (x>9)?x:'0'+x;
}
function twelveHour(x){
   if(x==0){
      x=12;
   }
   return (x>12)?x-=12:x;
}
function displayTime(){
   document.getElementById('tP').innerHTML=eval(outputTime);
   setTimeout('displayTime()',1000);
}
function amPMsymbol(x){
   return (x>11)?'pm':'am';
}
function fixYear4(x){
   return (x<500)?x+1900:x;
}

var dayNames=new Array('Sunday','Monday','Tuesday','Wednesday','Thursday','Friday','Saturday');
var monthNames=new Array('Jan','Feb','Mar','Apr','May','Jun','Jul','Aug','Sep','Oct','Nov','Dec');
var outputTime="dayNames[timeSource().getDay()]+', '+leadingZero(timeSource().getDate())+' '+monthNames[timeSource().getMonth()]+' '+fixYear4(timeSource().getYear())+' '+twelveHour(timeSource().getHours())+':'+leadingZero(timeSource().getMinutes())+':'+leadingZero(timeSource().getSeconds())+amPMsymbol(timeSource().getHours())";
I simple save the above in a .js file. Then, in your page, have the following code:

Code:
<span id="tP">
    <script language="javascript" type="text/javascript" src="clock.js">
         //<![CDATA[
        displayTime();
         //]]>
     </script>    
</span>
The original, generated script had an extra line that automatically loaded the script without the need of calling displayTime() in the <span></span> above. However, this generated JavaScript errors in IE7...so I eventually came up with the above solution.