Up-to-date Windows Installation Media

Use the Deployment Image Servicing and Management (DISM) tool to manipulate the image. DISM.exe gets shipped with Windows 7. You can integrate updates or drivers and even language packs.

prerequisites:
First you need an ISO-Image of a windows 7 Boot-DVD and an empty USB-stick with more than 6GB space.
If you have a Windows DVD SP1, create an ISO-Image e.g. with http://www.imgburn.com/

Next, create a Windows boot stick:
download the Windows USB/DVD Download Tool. e.g. from http://wudt.codeplex.com/
Install and follow the 4 steps to create the stick. (ALL DATA on the STICK will be LOST)

get Windows Updates:
Install the WUD - Windowsupdatesdownloader from
http://www.windowsupdatesdownloader.com/
get the latest update list from:
http://www.windowsupdatesdownloader.com/UpdateLists.aspx

or download other windows updates (file format: .msu, .cab)

Copy all updates into a single folder - no subdirectories.

main part:
Run following commands in elevated command window.

- mount image file:
dism.exe /Mount-Wim /WimFile: /Index:#2 /MountDir:
path to the Windows installation image file (e.g. f:\sources\image.wim)
empty directory on your local drive (e.g. c:\winimage)

- add updates
dism /image: /Add-Package /Packagepath:
folder path with all the update files or full path to single update (repeate if needed)

- unmount the image and write back all changes:
dism /Unmount-Wim /MountDir: /Commit
will write the image.wim on the usb-stick and delete content of

Now boot a new PC with this stick and all updates will be applied during installation. You will only have to load some new updates from Windows Update.

DISM provides some more options, e.g. remove updates or add drivers. Refer to the DISM help for further instructions: http://msdn.microsoft.com/de-de/library/hh825099.aspx