Hi, Randy.  Here's one solution.  I used code from the Word MVP site -
http://www.word.mvps.org/FAQs/MacrosVBA/GetCurUserName.htm - provided by
Astrid Zeelenberg.  The function code must be in a regular module.  I called
it from a UserForm with a label and two command buttons.

Here's the module code:

Option Explicit

'Declare for call to mpr.dll.
Declare Function WNetGetUser Lib "mpr.dll" _
       Alias "WNetGetUserA" (ByVal lpName As String, _
       ByVal lpUserName As String, lpnLength As Long) As Long

Const NoError = 0    'The Function call was successful

Function GetUserName() As String

'Buffer size for the return string.
Const lpnLength As Long = 255

'Get return buffer space.
Dim status As Integer

'For getting user information.
Dim lpName, lpUserName As String

'Assign the buffer size constant to lpUserName.
lpUserName = Space$(lpnLength + 1)

'Get the log-on name of the person using product.
status = WNetGetUser(lpName, lpUserName, lpnLength)

'See whether error occurred.
If status = NoError Then
   'This line removes the null character. Strings in C are null-
   'terminated. Strings in Visual Basic are not null-terminated.
   'The null character must be removed from the C strings to be used
   'cleanly in Visual Basic.
   lpUserName = Left$(lpUserName, InStr(lpUserName, Chr(0)) - 1)
End If

'Display the name of the person logged on to the machine.
GetUserName = lpUserName

End Function

Sub ZZ_TimeStamp()
 UserForm3.Show vbModeless
End Sub

Here's the UserForm code:

Dim strStamp As String
Dim strUser As String
Dim strDate As String

Private Sub CommandButton1_Click()
 Selection.Range.Text = strStamp
End Sub

Private Sub CommandButton2_Click()
 Unload Me
End Sub

Private Sub UserForm_Initialize()
 strUser = GetUserName
 strDate = Format(Date, "dd mmm yyyy")
 strStamp = strUser & " - " & strDate
 Label1.Caption = strStamp
End Sub

HTH
Ed