Function Main()
Dim oFSO
Dim sSourceFile
Set oFSO = CreateObject("Scripting.FileSystemObject")
sSourceFile = "C:\SourceFile.txt"
' Check if file exists to prevent error
If oFSO.FileExists(sSourceFile) Then
YourAction
End If
' Clean Up
Set oFSO = Nothing
Main = DTSTaskExecResult_Success
End Function