reading UTF7,UTF8,UNICODE text file

Me.RichTextBox1.Text =My.Computer.FileSystem.ReadAllText(Me.OpenFileDialog1.FileName)

so that it will read correctly notepad files (UTF-7?) and any other valid text file?

I have addedImports System.text to my file but don't really know what to do next. I have tried various forms on encoding.xxxxx but all I get is errors. I have spent 2 days on this I seem to chase my tail looking at different treads.

ps my files contain extended chars set 128-255

[952 byte] By [samperiau] at [2008-2-8]