C# HTMLDecode without System.Web possible?

Developers who need to use System.Web.HttpUtility in their client apps and had to reference System.Web.dll and therefore target NET4 full (System.Web.dll is in Full) , can now target the NET4 Client Profile by using the new System.Net.WebUtility class which is in System.dll (System.dll is in NET4 Client Profile). System.Net.WebUtility includes HtmlEncode and HtmlDecode. Url encoding can be accomplished using the System.Uri class (also in System.dll).

From http://blogs.msdn.com/b/jgoldb/archive/2010/04/12/what-s-new-in-net-framework-4-client-profile-rtm.aspx

You can use System.Net.WebUtility.HtmlDecode:

Converts a string that has been HTML-encoded for HTTP transmission into a decoded string.

Just because you're writing a Windows Forms app doesn't stop you from using System.Web. Just add a reference to System.Web.dll.