Windows 7 does not include a GUI to disable the taskbar thumbnail preview feature. I’ve experimented with the registry setting TaskbarNoThumbnail and its equivalent GPO Turn off taskbar thumbnails. That setting seems to apply only to Windows Vista, and has no effect in Windows 7.

You can however disable the taskbar thumbnail feature (sort of) in Windows 7 using a registry edit. This can be done by setting the taskbar thumbnail preview hover delay to a large value (say 10000 milliseconds or more), so that the preview is not immediately generated when you hover over a taskbar icon. Well. Then the article title should have really been "How To Delay Taskbar Thumbnail Preview in Windows 7".
I heard about this registry value via article Adjust Taskbar Preview Hover Delay at WinGeek.com (Credits to Steve Sinchak), and experimented the registry value by inputting a large decimal value to prevent immediate display of thumbnails in the Windows 7 Taskbar.
1. Click Start, type Regedit.exe and press {ENTER}
2. Navigate to the following location:
3. Create a new DWORD (32-bit) value named ExtendedUIHoverTime
4. Double-click ExtendedUIHoverTime and click Decimal
5. To increase the hover delay to 5 seconds, type 5000. Type 10000 for 10 seconds and so forth…

6. Exit the Registry Editor.
7. Logoff and login back, or restart the Shell ("Exit Explorer" method).
Related Article
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