Dato che ora l'ho cancellato, lo riscrivo a memoria:
codice:
    Private W As IO.StreamWriter
Private Sub bgConvert_DoWork(ByVal sender As System.Object, ByVal e As System.ComponentModel.DoWorkEventArgs) Handles bgConvert.DoWork
        Dim Info As ConvertInfo = e.Argument
        Dim Lame As String = Application.StartupPath & "\lame.exe"
        Dim P As Process
        Dim Index As Int32 = 0

        bgConvert.ReportProgress(0, Info.Files.Count)
        For Each File As String In Info.Files
            P = New Process
            P.StartInfo.FileName = Lame
            P.StartInfo.Arguments = Info.Arguments & String.Format("{0}{1}{0} {0}{2}{0}", Chr(34), File, Info.Folder & "\" & IO.Path.GetFileNameWithoutExtension(File) & ".mp3")
            P.StartInfo.UseShellExecute = False
            P.StartInfo.RedirectStandardOutput = True
            P.StartInfo.CreateNoWindow = True
            W = New IO.StreamWriter("output.txt")
            AddHandler P.DataReceived, AddressOf Process_DataReceived
            P.Start()
            P.BeginOutputReadLine()
            P.WaitForExit()
            RemoveHandler P.DataReceived, AddressOf Process_DataReceived
            W.Close()
            Index += 1
            bgConvert.ReportProgress(Index, Info.Files.Count)
        Next
    End Sub

    Private Sub Process_DataReceived(ByVal sender As Object, ByVal e As DataReceivedEventArgs)
        W.WriteLine(e.Data)
    End Sub
Grossomodo era questo.