Windows 7 taskbar groups to use vertical menus only, not thumbnails?

There's a registry key you can edit to get this behaviour even in modern versions of Windows 7:

HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\Taskband

Create a DWORD called NumThumbnails, and set it to 0 to achieve list mode for all taskbar groups.

Alternatively, you can set it to a number such as 3 or 4. Then apps with that many or fewer windows will use the thumbnails interface, but apps with more than that many windows will use the list mode.

This is my preferred setup, so that things like Outlook and Word still use thumbnails when I have 2-3 windows open, but Chrome and Windows Explorer (for which I typically have 10-15 windows open each) use the more informative list mode ("vertical menus").

Source: http://www.sevenforums.com/tutorials/75804-taskbar-list-thumbnail-previews-mode-change.html

I came across this post while looking for an answer for this same issue.. One thing I've found -- if you go into Control Panel > System > Advanced System Settings > Performance 'Settings' and uncheck 'Enable Desktop Composition' it will remove most Aero features, but it does give you a consistent vertically listed taskbar menu.

I like the regular Aero desktop visuals, so I'm kind of torn -- a pretty interface or a functional one.

Unfortunately at this time Microsoft won't let me do both!!!

Overall, the new task bar, 'pinning' of icons, Gigantic icon preview windows, and 'frequently used' lists are totally STUPID and USELESS.

-Silas