An Official Microsoft website (https://www.microsoft.eu/) for Europe appears to be having struggles loading and hackers have made claim to this. The claims appear to first come from Anonymous Squad 35 @AnonSquadNo035 who announced the attack on facebook and twitter. > Tangodown – > microsoft.eumicrosofteurope.eumicrosoft-test.zn4.be microsofteurope.eu lulz ^_^… fb.me/20PmBLkHA — AnonymousSquadNo.035 (@AnonSquadNo035) January 23, 2013
At time of publishing the site was still being slow to load but i can confirm this was down for only a short period of time. 
A user with the handle @pronaxx on twitter also announced it was down globally with the following screen cap. 
And for those who are concerned this may not be a Microsoft website check the details here.