Windows 7′s taskbar is called “Superbar” and by default it shows only big icons of the running or pinned applications without their names. This feature is very similar to that of Apple’s. When you hover the mouse over an application icon, it shows the hidden running instances. While Some like this feature, others do not.
Windows7 Superbar Feature

To Get Windows Vista-XP like taskbar all you have to do is the following:
1. Right Click on an empty space on the taskbar
2. Select Properties
3. Check “Use small icons” and change the settings for Taskbar buttons to “Never Combine”
Taskbar Properties

After these changes are made, you will get the following:

If you want to have something more advanced like this:

GloomLevel

Thanls to by Clifgriffin.com

You have to edit the registry (don’t edit the registry if you don’t know) by doing the following:
1. Open regedit
2. Add a DWORD named TaskbarGlomLevel under the key :

"HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\Advanced"
3. Set the value to “1″ to enable Vista Functionality or to “0″ if you want to disable it.
4. Log off / Log in

The mod was found by Matt A. Tobin