This page lists both commercial and free alternatives to the HtmlEditor, with comments where possible about advantages and disadvantages.
VB.NET sample showing how to use the WebBrowser ActiveX control in a user control. Free.
Full featured wrapper for MSHTML. This control does not use the PIA and provides some additional features, like TableDesigner and Binary Behaviors. Commercial.
If you only need to view rather then edit HTML, there is an other nice one (commercial and expensive) here:
it's fully managed (I mean it don't even use IE runtime)
And there is also this one:
http://www.windowsforms.net/ControlGallery/ControlDetail.aspx?Control=290&tabindex=0 - also see article describing the control at
http://www.codeproject.com/useritems/csEXWB.asp - Another .NET 2.0 control which creates, hosts the original Webbrowser control.
http://www.modeltext.com/html/ - A fully managed control (no IE, no dependencies on unmanaged code). Supports XHTML (documents or fragments), WYSIWYM editing, the more important CSS properties, and DOM and Event APIs. Can run in a partial trust environment (in the 'Internet' security zone).