Contract Cancel - Created a dilemma for myself

Fellow Monkeys

Created a dilemma for myself. Recruitment season passed and I accepted an offer in S&T from a firm. Good firm, reputable, however, not my first choice.

My first choice was in IB with a firm that was much larger and much more respected at the time. I was denied my first choice. However, a recruiter from IB contacted me and said that a different group under the same department has an analyst opening.

As of right now I have chosen to interview again with the firm that is my first choice.

My dilemma:

1) I accepted the first firm's offer in Dec. 09. 2) I have no idea if I am allowed to renege on my contract? 3) My first choice firm, would offer more money as a first year analyst 4) How badly am I burning bridges with the first firm, if I get an offer from my first choice, and call up HR at the firm which I accepted and told them that I will no longer be able to be a part of the analyst class?

Any ideas would be a huge help, as I am pretty much freaking out that I could be making a wrong career choice or I might stuck in the first choice that I made.