We have a 1400 PCs Network and are using NetInstall 4.2 by firma NetSupport.
We will soon migrate to version 5.5, with Mutiserver support.
We are installing EVERYTHING: Office, Outlook, IE, Antivirus, Video and Sound Drivers, ...
Really great.
It uses a "Spy" to capture the installation on a test machine, and it can then reproduce it on any machine, even if the user doesn't have the right (it uses an easy remotelly installable service).
The "script" of installation can be easily edited using its GUI, so you can add customization to the "spied" script.
InstallShield has bought the technology and distributes the English version (original is German).
Now it also supports Microsoft Installer format (MSI).
It may seem I am getting moneyfrom them (I am not) but the truth is that it is very good.