display html string formatted

Hi,
That's easy question - how can I display content of my string formatted as html? (without 3rd party tools)

I haven't find any way to pass it to RichTextBox, also WebBrowser seems too complex and complicated (and I am not able to create new HtmlDocument as it doesn't have any constructors).

For those happy with VisualStudio 2005 I'm looking for something like HTML Visualizer.

Thanks for help