string targetkey = @"SOFTWARE\Microsoft\NET Framework Setup\NDP";

//get an array of subkeys of target key - these will be installed versions of dot net
RegistryKey dotnetkey = Registry.LocalMachine.OpenSubKey(targetkey);
string[] installedversions = dotnetkey.GetSubKeyNames();

//wrap array into list
List<string> versionlist = new List<string>(installedversions);

Module ExtensionMethods
    Private EmptyDelegate As Action = AddressOf EmptyMethod
    Private Sub EmptyMethod()

    End Sub

    <System.Runtime.CompilerServices.Extension()> _
    Private Sub Refresh(ByVal uiElement As UIElement)
        uiElement.Dispatcher.Invoke(EmptyDelegate, Windows.Threading.DispatcherPriority.Render)
    End Sub

    Public Function FrameWorkCheck_35SP1() As Boolean
        Dim retVal As Boolean = True
        Try
            Dim x As New TextBox
            x.Refresh()
        Catch ex As Exception
            retVal = False
        End Try
        Return retVal
    End Function

End Module

string targetkey = @"SOFTWARE\Microsoft\NET Framework Setup\NDP";

//get an array of subkeys of target key - these will be installed versions of dot net
RegistryKey dotnetkey = Registry.LocalMachine.OpenSubKey(targetkey);
string[] installedversions = dotnetkey.GetSubKeyNames();

//wrap array into list
List<string> versionlist = new List<string>(installedversions);