Non competition valid after 11yrs service?

I signed a Employment Agreement with a Non Compete clause in 1997. The company was one of the holding companys of the US parent. Since then the Parent has split itself into many holding companies, sold off some during the 2000 dot com bubble, then merged its holding companies back into 2 main ones, changed its name again, payslips started to reflect the new holding company... then the revised name, then it sold the original company I had signed an agreement with. Now the only signature on an employment contract is the one from 1997 and that company has been sold. The company has also let their other employees join the customer or client where they worked over the years. They have made enough money by paying 1/2 of the PA wages for my position with no training or other career advancement opportunities. Even though I am an Exempt, they have not paid so in the past. Is non compete valid.