Made a simple QRCode reader in .Net the other day.  I used the Open Source ZXing barcode processing library.  You need to build the C# code, which was easy enough with C# express 2008, then add the dll as a reference to your project.  This code is in vb2008.  I created a simple QR Barcode using the ZXing tool. 

'Need to reference the System.Drawing assembly from .Net 2.0 if you are working with VB 2008 .Net 3.5 

Imports com.google.zxing
Imports System.Drawing.Bitmap
Imports System.Drawing


Class Window1

    Private Sub button1_Click(ByVal sender As System.Object, ByVal e As System.Windows.RoutedEventArgs)
        Try
            Dim re As Reader
            re = New qrcode.QRCodeReader
            'Created a new qrcode reader...  

            'Created a bitmap from the QR code download

            Dim Img As New Bitmap("C:\workspace\geochart.png") 'location where I saved the image

            'In XAML I have an image object named imgQR so I can see it.

           imgQR.Source = New System.Windows.Media.Imaging.BitmapImage(New Uri("c:\workspace\geochart.png"))

            Dim bufimg As com.google.zxing.client.j2se.BufferedImageMonochromeBitmapSource 'not sure what this does
            bufimg = New client.j2se.BufferedImageMonochromeBitmapSource(Img, False)
            Dim res As com.google.zxing.Result = re.decode(bufimg) 

            tb1.Text = res.getText() 'raw text
        Catch ex As Exception
            MessageBox.Show(ex.ToString)
        End Try
    End Sub
End Class