BRUSSELS (Reuters) - European Union regulators fined Microsoft (MSFT) 280.5 million euros ($357.3 million) on Wednesday for defying a 2004 antitrust ruling, and warned the company to comply or face bigger fines from next month. The tough new penalty is the first of its kind and comes on top of a record 497 million-euro fine the Commission imposed in its landmark antitrust decision against Microsoft in March 2004. "Microsoft has still not put an end to its illegal conduct. I have no alternative but to levy penalty payments for this continued non-compliance," Competition Commissioner Neelie Kroes said. "No company is...