Today I read Hanno's blog entry about his failed Microsoft Windows Vista refund. He used the same formula as I did. He got the answer (rough translation):
We won't refund your windows-license, because we think it's an integral part of the product.
Side not: I got 30 EUR without any answer on my bank account.
As you might know we have a Windows tax refund where we want to summaries all essential information about this topic. (Yes the page is in the first beta ;) ).
If you have information about Windows tax refunds, especially Lenovo with in Germany at the moment, please report your experience to FSFE's German Team under firstname.lastname@example.org.