Subject + used to + infinitive is used to refer to things in the past which are no longer true. It can refer to repeated actions or to a state or situation.

Subject+ would + infinitive is used only for repeated actions, not for a state or situation.

http://learnenglish.britishcouncil.org/en/quick-grammar/past-habit-used-towouldpast-simple http://dictionary.cambridge.org/grammar/british-grammar/past/used-to