You will need to do an Anyime Upgrade to Windows 7 Ultimate, then download the Dutch Language through Windows Update:
Upgrade to another edition of Windows 7 by using Windows Anytime Upgrade
Here is an example how to download a language pack, install and configure it:
Before you can start using a language in Windows 7 Ultimate, you must first download and install it. Microsoft offers up to 35 different multi-lingual user interfaces through its Windows Update service. Lets take a look at how to install and configure one. For the purposes of this review, we are gonna install Spanish.
First, launch Windows Update.
Click Check for updates.
Click the optional updates are available link.
Here you will see a list of available languages for download. Check the desired language you would like to have installed, then click OK.
You will be taken back to the main screen, click Install update.
Wait while the update is downloading.
Installing the Language Pack
After the installation has completed, we will now enable the language pack.
Click Start, then type: language.
Hit Enter on your keyboard.
Click on the Keyboard and Languages tab.
Under Choose a display language, click in the list box and select the language you want to have displayed.
Click Apply and then OK.
You will be prompted to Log off now. Do so then log back in.
That’s it, you are now operating in Windows 7 using a different language.
When you are ready to change back to another language, just reopen the Region and Language dialog and select your default language.
That’s It!
