|You can create a Macro that uses the Open event.|
1 - In Workbook 1, use Alt-F11 to open the VBA editor.
2 - Double click the ThisWorkbook module and put something like this in the pane:
Private Sub Workbook_Open()
Workbooks.Open Filename:= "W:\MyWorkbook2.xls"
3 - Open Workbook2 and Hide it.
4 - Exit Excel, clicking Yes to Save Workbook1 & 2
The next time you open Workbook1, Workbook2 should open Hidden.