you can also check out the IE Developer Toolbar which isn't a debugger but will help you analyze the contents of your code.
Visual Studio will help with the debugging
Fiddler should help analyse the traffic travelling to and from your browser
Read more... Read less...
Since Internet Explorer 8, IE has been shipping with a built-in tool-set for debugging, troubleshooting, and generally helping in development of your pages/applications. You can access these tools by pressing F12 while in the browser.
The HTML tab will let you peek into the DOM as the browser understands it. As you select elements from the HTML view, their styles will be detailed on the right, with individual rules have the ability to be toggled on and off. You can also modify rules, and determine whether the styles on the element were inherited, or assigned explicitly. Additionally, you can even tell which .css file they originate from.
There is a bit more you can do in the HTML tab, such as review and modify attributes on elements, and even make changes to the layout of the element from within the layout section. Additionally, you can make changes directly to the markup to quickly test out some structural ideas.
If you've used Firebug, or even the Webkit Inspector, the F12 Developer Tools in Internet Explorer 8+ should be pretty familiar to you.
Firebug lite doesn't work too well for me. The Developer Toolbar just isn't good enough. There really is no great solution.