IANAL, but...
whether OEM or wrapped retail CDs it's obviously full of... slippery things. To begin with, unholy combination of 2 contracts: offer to public at large from shop and EULA from M$ - with whom EXACTLY you're dealing in what, or to which degree ? Normally manufacturer can be involved only via "consumer protection". If it's not yours until you submit (or even after) - then what EXACTLY did you just purchased in shop and what shop itself did bought from M$ ? And this inevitably leads to "uh, ask third party's home rules" crap. "Sticker-based" contracts ? Come on. Suppose you'll buy something in closed envelope and it turns out to contain note "uups, you owe me 1000$", or "by opening this you gave any passer-by right to strip-search you". Isn't it the same ? Agreement with content changeable without even prior notice ? Great. They already smuggled some interesting things there, and who can say it's the top of their imagination ?
http://www.infoworld.com/articles/op/xml/02/02/11/020211opfoster.html
@ Adam: if you could catch food manufacturer doing what M$ and their subsidiaries do, it could be rather sensible idea to send *missiles*, not sausages. If arrested, just produce their EULA and claim self-defence. =)))