Combo box & Saving

Ok,
I'm having problems with my final project.
First,
How can I limit the values in a combo box????
Example: I have a combo box with values 2,3,4.
When the user goes to that combo box to chose one and enters any other data, it accepts it. I don't want that!!
HELP!!!

Second,
What do I do to save a record in a file? The file is created but will start off wit no records. Do I Open for Output, and then what? It's not working.......

Code:

---

Option Explicit

Private Sub Combo1_KeyPress(KeyAscii As Integer)
'keep text from being entered in combo1
    KeyAscii = 0
End Sub

Private Sub Command1_Click()
'load combo with items
    Dim i As Integer
    For i = 1 To 4
      Combo1.AddItem i
    Next i
   
    Dim myFile As String
    Dim intNum As Integer
   
    myFile = "C:\my documents\myfile.txt"
    intNum = FreeFile
'if you use output you overwrite, append adds to the bottom
'of existing file, and input reads

    Open myFile For Output As intNum
'save the contents of the combobox to a file
      For i = 0 To Combo1.ListCount - 1
        Combo1.ListIndex = i
        Print #intNum, Combo1.Text
      Next i
      Close #intNum
      Combo1.ListIndex = 0
End Sub

---