Outlook 2007 has a new feature that allows you to preview attachments and documents if the handler is available for that filetype. However, some users do not use (or like) this functionality. To turn off Attachment Preview, follow these steps:
1. Click Tools and select Trust Center.
2. In the left pane, select Attachment Handling.
3. In the right pane, under Attachment and Document Preview, uncheck the Turn off Attachment Preview checkbox. If you only want to disable Attachment Preview for certain types of files, leave the checkbox checked and click the Attachemnt and Document Previewers button. From the File Previewing Options window, uncheck the previewers that you do not want to use.
4. Click OK to close the window(s).