Visual Web Developer is probably your best bet. It's free and provided by Microsoft, so it'll work and play nicely with the standard .NET control set. It's not as full featured as Visual Studio is, but for a free tool I don't think you're going to get any better than this.
That being said, you really need to learn the client end of developing ASP.NET, since there's only so far any WYSIWYG editor is going to go.