When you use the open dialog box to open any Excel workbook, some files dis¬playa preview of the workbook and some don't. If you want all your Excel files to show a preview you need to save the pre¬view when closing the file. Here's how:

1.First open the workbook and select Office > Prepare > Properties. Excel will display some of the workbook's properties.

2.Click the Document Properties drop-down list (found at top-left corner of the visible properties) and choose Advanced. Here, make sure the Summary tab is selected.

3.Select the Save thumbnails for all Excel Workbooks check box and click OK to close the properties dialog box.