I was rear-ended by a state vehicle in March 2009 their claims department hasnt paid yet. What are my rights?

In Colorado there is a statutory requirement that formal notice be provided a state entity if you intend to file a neglgience lawsuit against the entity, and this notice must be given the state within 180 days of the accident. So if your accident occurred in March, then it has been over 180 days and you probably are barred from filing a lawsuit. Without the threat of a lawsuit you have little bargaining power. You should consult with a Colorado attorney to determine if you may have satisified the notice requirement with your earlier correspondence with the claims department - that may be your hope.

The information provided to you in this answer is not, nor is it intended to be, legal advice. You should consult an attorney for advice regarding your individual situation if you have further questions.