Examine http response headers in IE8

I'm looking for an ie8-addon that displays the http headers like firebug or httpliveheaders do. Any advice is appreciated.

edit: I may be blind but it seems as if the built-in developer tools (F12) do not show the http headers.

You might be looking for Fiddler2

Fiddler is a Web Debugging Proxy which logs all HTTP(S) traffic between your computer and the Internet. Fiddler allows you to inspect all HTTP(S) traffic, set breakpoints, and "fiddle" with incoming or outgoing data. Fiddler includes a powerful event-based scripting subsystem, and can be extended using any .NET language.

Fiddler is freeware and can debug traffic from virtually any application, including Internet Explorer, Mozilla Firefox, Opera, and thousands more.

If you want to view HTTP headers in your IE I recommend using DebugBar.
I've tested it with IE8 and it was working with no problems. It has also few other useful features like validating HTML or viewing cookies.

However I see two problems with this tool:

• for personal use it is for free, otherwise you have to pay.
• dynaTrace had some compatibility issues with DebugBar.

Not a full answer, but a step in the right direction:

In http://blogs.msdn.com/b/ie/archive/2010/04/22/ie9-developer-tools-network-tab.aspx it says:

The [IE9] developer tools include some new capabilities and improvements over the tools in IE8:

A new tab for inspecting network traffic.

So inspecting network traffic is impossible in IE8 Developer Tools. You'll need to install something else. See the other answers for final solutions.