You have enough friends without her.
That said, your chances are low. 1) She loves her boyfriend. He's probably smarter, richer and better looking than you. 2) You're on the friend ladder. Screw with the ladder and you could find youself watching Monday night football alone.
Remember, most couples do not end up married. Chances are he'll screw up, or he'll get sick of her. Remember this mantra: "Show me a hot girl, I'll show you a guy who tires of her".
The best thing for you to do at this point is to "get in line" -- anything else and you'll hurt your chances. Once they're done, you can be her rebound guy if you want. Remember, time is the ultimate test. If you and her are meant to be with each other - mother time will take care of the rest.
Jack