Despite the fact Windows 7 has been in circulation since before October 2009 there still appears to be no official support for the Microsoft Exchange System Management tools for the Active Directory Users and Computers Microsoft Console applet (dsa.msc).
Luckily there is a work around to enable the installation of Windows Vista Exchange System Management tools on Windows 7.
All you need to do is, download a copy of the MSI from here extract the contents to a folder of your choice, and then run the following from the command line:
MSIEXEC /IESMVISTA.MSI /Q
Doing this will prevent the MSI checking that you are running Windows Vista and should install without any issues.
Restarting Active Directory Users and Computers should enable the add-on and you should now see the additional tabs as pictured in the screen shot above.