I consulted a solicitor about one such non compete clauses in an employment contract a few years back and she told me that the clause was basically unenforceable under Irish/EU employment law. Obviously this does not prevent an employer from protecting themselves against employees who steal intellectual property etc. (e.g. plans, designs, software code, customer lists etc. - usually covered by another claused in a contract of employment) but I don't think that they can generally do anything about you going to work for another company, competitor or not, regardless of such non compete clauses.