Actually, I have everything working at this point with the code below, accept whent the focus is set back on the control, if the user does not make any changes to the text box it is not checked again..... 

Protected Sub itemPlotSummaryTextBox_TextChanged(ByVal sender As Object, ByVal e As System.EventArgs)
        Dim tb As TextBox = DirectCast(FormView1.FindControl("itemPlotSummaryTextBox"), TextBox)
        Dim tooLong As Integer
        tooLong = tb.Text.Length
        If tooLong > 100 Then
            MsgBox("The Plot Summary is too Long. The field is liimited to 100 characters, the field is currently " & tooLong & " characters in length.")
        End If
        SetFocus(FormView1.FindControl("itemPlotSummaryTextBox"))


    End Sub

I guess the validator is the better option, I try and convert to that in VB though.

I am a bit miffed on the validator though. I'll post my progress shortly.