While the EULA of OS X might not hold water in the EU, it has yet to be tested. So Apple is proceeding as if US law applies. As such, getting a retail copy of OS X to run on generic PC hardware is none too pleasant. And system updates are likely to break your system. So it's not highly recommended. Basically, if you want a 'headache-free'* OS X machine, just buy a Mac. Or alternatively, if you want to keep your current PC hardware and get a more robust OS. Install one of the many Linux distributions.

* 'Headache-free' in relative perspective, no complex system is free of bugs. OS X doesn't magically make hardware and software problem free. Apps still crash, updates still fail.