Select Pre-installed Windows 7 Home Premium in English, for instance. You get a PDF to download.
Here's one of several clauses that describe how YOU ARE CONSENTING IN ADVANCE that Microsoft can scan your computer for software / media / documents (see also "Digital Rights" for instance) that are illegal / harmful / unlicensed, in their opinion, and delete or disable those items, or your entire computer:
"The software will from time to time perform a validation check of the software. The check may be initiated by the software or Microsoft. To enable the activation function and validation checks, the software may from time to time require updates or additional downloads of the validation, licensing or activation functions of the software. The updates or downloads are required for the proper functioning of the software and may be downloaded and installed without further notice to you. During or after a validation check, the software may send information about the software, the computer and the results of the validation check to Microsoft. This information includes, for example, the version and product key of the software, any unauthorized changes made to the validation, licensing or activation functions of the software, any related malicious or unauthorized software found and the Internet protocol address of the computer. Microsoft does not use the information to identify or contact you. By using the software, you consent to the transmission of this information. For more information about validation and what is sent during or after a validation check, see go.microsoft.com/fwlink/?Linkid=104611.
"c. If, after a validation check, the software is found to be counterfeit, improperly licensed, or a non-genuine Windows product, or if it includes unauthorized changes, then the functionality and experience of using the software will be affected. For example:
· repair the software, and remove, quarantine or disable any unauthorized changes that may interfere with the proper use of the software, including circumvention of the activation or validation functions of the software; or
· check and remove malicious or unauthorized software known to be related to such unauthorized changes; or
· provide notice that the software is improperly licensed or a non-genuine Windows product;
and you may
· receive reminders to obtain a properly licensed copy of the software; or
· need to follow Microsoft’s instructions to be licensed to use the software and reactivate;
and you may not be able to
· use or continue to use the software or some of the features of the software; or
· obtain certain updates or upgrades from Microsoft."
With the legal language they use, they are allowed to do almost anything.
P.S. Most of this language also applies to only updating Windows Media Player.