You could launch excel again, then open the file from the new excel, but you'll notice a file in use message which will allow you to open your personal.xls file as read-only for the second instance of excel.
If you have workbooks open in one instance of excel, you can toggle through them by using ctrl+tab, or you could tile them by using the menu options Window>Arrange...> then choose how you want the workbooks displayed.
In my opinion it is not good practice to open a new version of excel for new spreadsheet yo need to open. You'll soon eat up system resources. The other suggestion of window arrange works, but if excel and the current window are fully maximised any new spreadsheet launched should take up the current window.