iframe style="WIDTH: 400px; HEIGHT: 300px" src="http://www.drivehq.com/file/df.aspx/publish/rex_hansen/SampleCode/ArcGIS_SOAP_Silverlight_AppTestPage.html" frameborder="0" scrolling="no"
ESRI Silverlight Map Control Example
Make sure you close the iframe tag, or it won't work.
Enjoy