Non-competes may be enforceable. The answer differs on a state-by-state basis. Generally speaking though you must have some element of unfair advantage that you can bring to a new employer, such as knowledge of customer lists, trade secrets, etc.
Unfortunately for you, even if the agreement is unenforceable, your current firm can threaten your new employer with a tortious interference claim in the event the new firm causes you to violate your non-compete. In this situation, your new employer may rescind your job offer rather than risk the ensuing battle. In such a case, you need to be prepared to challenge the actions of your current- and soon to be former- employer.
ETA: Just checked my 50 state guide to non-competes and they are enforceable in Illinois. Further, Illinois courts will tend to narrow them when overbroad, not simply invalidate, which is not a good development for you.
What do you do and what pecularized knowledge of your employer do you have?