Joining Competitor Company

Hi ,
My appointment letter says , i cannot join a competitor company for a period of 2 years after leaving my current company. I have not signed any legal document with my current comapany .I have received a good offer from a competitor company , if i join this company. Can my current company sue me on my appointment letter.
regards

dear
you can join in other company.the clause given in appointment letter is not correct.see if iam working as a chemist in pharmaceutical company and i leave the company and join another company that will also be pharaceutical.it means after leaving the prsent company i should not work anywhere for two years.what a stupid clause it is?
as per indian contract act 1972 section 27 this agreement in the form of appointment letter is void.
section 27 says---every agreement by which any one is restrained from excercisinga lawful profession,trade or business of any kind ,is to that extent void.
regards
js malik

so i can join competitor without any fear of legal issues? although it is mentioned in my appointment letter not to join competition.