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Your easiest way round your problem would be a Windows Anytime Upgrade from Windows 7 Professional to Windows 7 Ultimate, which would give you access to 34 language packs via Windows Updates. http://emea.microsoftstore.com/UK/en...nytime-Upgrade
Obviously, you'll need to choose your region before you make your purchase, but all it involves is buying a new product key, which is then e-mailed to you.
Then it's Start>All Programs>Windows Anytime Upgrade and follow the instructions to enter your new product key.
Wait half-an-hour or so and it's job done.