I have just been through this silly thing of trying to look at two different Excel workbooks. I wanted to view them side by side but as I clicked on one it replaced the other one. I googled, as you do, and found this helpful advice on the Microsoft support site. If you open two workbooks they are down on the taskbar and you can switch between them by clicking on the relevant one. If you want to view them simultaneously you have to go to View and Arrange All. Easy when you know how! I am using Office 2007. I have other version but his one is my favourite.