[michaelpinto]

1. Is this something you want to spend time and money on?

2. If the above answer is yes, is the other party in a position to not care about time and money?

3. If the above answer no, and if you can prove that your trademark is older then talk to a lawyer.

4. Find out the following from the lawyer: If your case is strong, and how much money and time might be require to defend the trademark. Then and only then would I go ahead. And even then I'd see if I could talk to the other party (if my lawyer told me I was in the right) and settle the case.

Another cost factor: Is going the legal route more expensive than a rebrand?

And also keep in mind that sometimes you can be talking to a lawyer who just wants to rack up billable hours. So try to find one that really knows about IP and comes recommended to you...