>Microsoft monitoring is opt-in, not opt-out.

http://privacy.microsoft.com/en-us/fullnotice.mspx#EZG

Display of Advertising (Opt-Out)
Many of our Web sites and online services are supported by advertising.
Most of the online advertisements on Microsoft sites are displayed by Microsoft Advertising. When we display online advertisements to you, we will place one or more persistent cookies on your computer in order to recognize your computer each time we display an ad to you. Because we serve advertisements on our own websites as well as those of our advertising and publisher partners, we are able to compile information over time about the types of pages, content and ads you, or others who are using your computer, visited or viewed. This information is used for many purposes, for example, it helps us try to ensure that you do not see the same advertisements over and over again. We also use this information to help select and display targeted advertisements that we believe may be of interest to you.
You may opt-out of receiving targeted ads from Microsoft Advertising by visiting our opt-out page. For more information about how Microsoft Advertising collects and uses information, please see the Microsoft Advertising Privacy Supplement.
We also allow third-party ad companies, including other ad networks, to display advertisements on our sites. In some cases, these third parties may also place cookies on your computer. These companies currently include, but are not limited to: 24/7 Real Media, aCerno,Inc, AdBlade, AdConion, AdFusion, Advertising.com, AppNexus, Bane Media, Brand.net, CasaleMedia, Collective Media, Fox Interactive, Interclick, Millennial, PrecisionClick, ROI Media, Social Media, SpecificMedia, TrafficMarketplace, Tribal Fusion, ValueClick, Yahoo!, YuMe, and Zumobi. These companies may offer you a way to opt-out of ad targeting based on their cookies. You may find more information by clicking on the company names above and following the links to the Web sites of each company. Many of them are also members of the Network Advertising Initiative or the Digital Advertising Alliance, which each provide a simple way to opt-out of ad targeting from participating companies.

It might be my bad English, but I do not find the use of "may" very reassuring, specially noting that they do say "we will place one or more persistent cookies", there is no may in there but certainty.