I am aware that,
The last post in this thread was 1008 days ago.
...but since google search still sends people here who are seeking a solution to this dilemma, let me offer the what worked for me. Step 1:
Download & Install "Taskbar Tweaker" from here: 7 Taskbar Tweaker - RaMMicHaeL's home page
(Video Demo & description included) Step 2:
Relevant Setting - Change "Show Thumbnail Preview (Default)" to one of the other options (eg. List, Tooltip, Nothing) Optional Step 3:
If you want to get rid of the annoying hover to cycle through window preview, also known as Aero Peek Display Instantly, follow steps here: Make Aero Peek Display Instantly (or Disable it) in Windows 7 - How-To Geek
You folks have helped many people (including me.) I hope this helps those who needed it.