Debugging JS and Ajax on IE

I am currently working through a problem and at the point of pulling my hair out. I have an Ajax process that pops up a nice little div on success. In Firefox, predictably, I see the pop-up window and all is well. In IE, the ajax process runs and I do not get the pop-up window.

Maybe I am a little spoiled using Firebug because I can see the details of the request, the DOM and other important runtime bits. In IE I get nothing useful.

After writing the hundredth alert( ' yadda ' ); command, I thought I would ask the community for input. What do YOU use to debug javascript and ajax requests in IE?

P.S. Any one who write 'The Microsoft Script Debugger' will be taken out back and shot.