By default, Windows 2008 Server does not show you thumbnails for files when viewing them in Medium, Large or Extra Large Icon modes. To be able to view the thumbnails of images for example, you will need to do the following :
– Open up explorer, or Computer
– Click on Tools, then Folder Options (Or click the Organise drop down, and select folder options)
– Click on the View tab
– Now you can deselect the check box for “Always show icons, never thumbnails”
– Click Apply, then OK.
You should now be able to view your thumbnails. See below for the Folder Options dialog box.