do you want to sue because the new guy "knows" now?
OR
do you want to sue because you think it will impede your ability to make money/move forward-upward in the company?
OR
are you looking for an "out" in the form of a settlement to make a few bucks? (hopefully not this)
in plain terms... WHY DO YOU WANT TO SUE THEM?
some things to think about.
If you sue, you are stopping any forward progress and they will basically cuckold you until you quit in your current company.
If you sue, and it comes up that you are sueing your current employer at a potential new employer... .you wont get hired. trust me... i don't care if they can't legally hold bias... they will.