Keeping with the control array you can shortan your code to this
Code:
Private Sub Comand1_Click() 

Dim i As Integer
Dim Retval as Integer

Retval = 1

For i = 2 To 5

    If Cint(Text(i).Text) > CInt(Text(Retval).Text) Then
        Retval = i

Next i

MsgBox "TextBox " & Retval & " Is The Highest."

End Sub
hope this helps