You'll need an application event that monitors when you open another workbook.
Put this in your personal.xls's project under the ThisWorkbook module.
You may have to modify your workbook_open event to include the code--you'll want
to merge the code into one procedure:
Option Explicit
Public WithEvents xlApp As Excel.Application
Private Sub Workbook_Open()
Set xlApp = Application
End Sub
Private Sub Workbook_Close()
Set xlApp = Nothing
End Sub
Private Sub xlApp_WorkbookOpen(ByVal Wb As Workbook)
Select Case LCase(Wb.Name)
Case Is = "book1.xls", "book2.xls"
Case Else
Exit Sub
End Select
Call YourMacroHere(Wb.Name)
End Sub
And I had this in a general module in my personal.xls workbook.
Option Explicit
Sub YourMacroHere(myName As String)
MsgBox myName
End Sub
You can read a lot more about application events at Chip Pearson's site:
http://www.cpearson.com/excel/AppEvent.htm