Affiliate Marketing Secrets

Can I buy a domain name that is the exact name of someone’s company or trademark?
I want to know if I can buy a domain name that is the name of an existing company but is a domain name that they havn’t claimed yet. If I was to register it (eg; www.microsoft.uk.org) would the company whoes name it is have any legal claim to the domain or would it be legally mine. Also, could I then use it to put adsense adverts on the website, being careful not to use any copyrited logos, emblems or trademarks, names, etc? Can I still write about the company (good things!) and spell out their name (eg, ‘ microsoft’) without fear of being sued, so long as I use a disclaimer to say that the site is not affiliated with that company and all trademarks belong to them, blah, blah? Many thanks! 🙂
I did find some info on the subject, but even this says it is a grey area. Basically, domain registras allow anyone the freedom to buy any domain name, yet there is nothing stopping a company from taking you to court for infringing on their copyright, especially if you are making money from it.
So what do we all think?