[hga]

but you are not obligated to sign unless they are compensating you adequately for what you are giving up

In the US, at least in general, this is a contract, and without the employee getting "consideration" it's not valid. And mere continued employment doesn't count, they'd have to give you something extra such as a raise or bonus.

[olefoo]

What I meant by 'not obligated to sign' was that there are more than a few paths open. Some of those paths involve separation from this employer. The original poster needs to figure out what his options are, and what he can do if he can't negotiate an outcome he finds satisfactory.