Well, lets explain it differently.
- If you can't read the EULA before Windows is downloaded on your computer - invalid, thats called "Culpa in contrahendo".
- If you can't read the EULA before Windows is installed on your computer - invalid (does not apply this time)
- If you can read the EULA before installation, it is not a EULA in the US sense of "you sell your soul to this company" but a "AGB", general terms and conditions, which are strictly regulated by the German code civil (§307pp BGB - it is a long listing of terms that you may and may not include in your AGB). Even if a company carefully translates its EULA into German language, it is not automatically valid. About 99% of the terms you can find in a US EULA are violating German laws.
Important when checking AGBs for validity is that you need to apply the laws in reverse ... first §309, then §308, and then finally §307. Lawyers need their jobs, after all. Also, this validity check is called a "blue-pencil-check", which means: When a term is not valid, it does not get limited to the legal limits, but stays in effect, but is completely removed from the contract.