Windows 7 - Number displayed for how many opened windows on taskbar buttons?

Due to my work specific I urgently need always to know, how many separately windows (documents) are currently opened in some running applications (mail client, browser, MS Word, Adobe Acrobat and some other).
In Window XP I'd used the option "Group similar taskbar buttons" in order to get this number: it was shown by default at the beginning of every grouped button at the taskbar. Is there any option to get the same in Windows 7?

I've made my Windows seven's taskbar to look almost as it looks in Windows XP (using "always combined" etc), but could not find any way to see the number of currently opened windows :=(

May be some third-party utility or via manually modifying the system registry?

Thanks for every idea!

P.S.
Yes, I'm aware of the fact, that each opened window is represented as an extra edge on the taskbar button, besides I can hover the mouse of the icon to see a thumbnail preview of the opened windows. But it does not give any actual benefit, if you have really MANY windows (e.g 15-20 windows is my usual practice for mail client).