[VBA]
Sub LatestFile()
Dim fdate, tmp, fname As String, LastFile As String
tmp = 0
fname = Dir("C:\AAA\*.xls")
Do
fdate = Split(fname, "of ")(1)
fdate = CDate(Split(fdate, ".")(0))
If fdate > tmp Then
tmp = fdate
LastFile = fname
End If
MsgBox tmp
fname = Dir
Loop Until fname = ""
Workbooks.Open ("C:\AAA\" & LastFile)
End Sub

[/VBA]