Thecontrol is designed to work in full trust only. The HTML content displayed in the control can come from external Web servers and may contain unmanaged code in the form of scripts or Web controls. If you use the WebBrowser control in this situation, the control is no less secure than Internet Explorer would be, but the managed WebBrowser control does not prevent such unmanaged code from running.
For more information about security issues relating to the underlying ActiveX WebBrowser control, see "WebBrowser Control" in the MSDN library at http://msdn.microsoft.com/library.
Windows XP Service Pack 2 provides technologies that help make Web browsing safer. Some of these technologies may affect the code you write when you use the WebBrowser control. For more information, see "Changes to Functionality in Microsoft Windows XP Service Pack 2 Part 5: Enhanced Browsing Security" (http://www.microsoft.com/technet/prodtechnol/winxppro/maintain/sp2brows.mspx).