Visual Basic - Cargar un archivo .txt en un textbox

Podrian pasarme un codigo fuente de que cuando haga click en un boton(command1), en un textbox(text1) me aparezca el texto de un archivo tipo .txt(c:\demo.txt) gracias a todos.

Fijate con esto:

Text1.Text=FileToString("c:\demo.txt")

Public Function FileToString(FileName As String) As String
Dim hlngFile As Long, strFile As String

hlngFile = FreeFile

Open FileName For Binary Access Read As hlngFile

FileToString = vbNullString

strFile = String(FileLen(FileName), " ")

Get hlngFile, , strFile

Close hlngFile

FileToString = strFile

End Function

Y para el proceso inverso (si te sirve)

StringToFile Text1.Text,"c:\demo.txt"

Public Function StringToFile(StringText As String, FileName As String) As Long
Dim hlngFile As Long

hlngFile = FreeFile

Open FileName For Binary Access Write As hlngFile

Put hlngFile, , StringText

Close hlngFile

StringToFile = FileLen(FileName)

End Function