Donatelli’s quit from EMC for HP is illegal?

Donatelli’s quit from EMC for HP is illegal?
It was announced that EMC is intended to enforce the non-compete clause to the court over its ex-executive VP David Donatelli, who is set to join HP.

Donatelli, a 22-year president of EMC's storage business with intimate and up to date knowledge of EMC's operations, storage roadmap, partnership with Cisco, strategies concerning VMware, and product and technology roadmaps, had suddenly resigned from his position. He is intended to join HP on May 5th as an executive vice president in charge of its servers, storage, and networking. He filed a law suit in California that attempts to render a non-compete clause in his EMC employment contract null and void. EMC, in return, retaliated by filing its own suit in Massachusetts that would enforce the non-compete clause and prevent him from joining HP.

Michael Gallant, EMC spokesperson, commenting on the issue said that Donatelli’s key employee agreement with EMC contained a non-competition clause and other protections that the company was set to enforce. A non-compete clause of the company aims to limit key employees taking jobs at its rivals, in order to prevent disclosure of trade secrets, customer information, etc. And in this case, HP and EMS are surely rivals as they both make and sell storage hardware and software.

It should also be noted that as legal support for non-compete clauses varies in USA states, California where Donatelli is suing EMC, does not uphold them at all, while Massachusetts does.