I just bought tickets to Boston through www.orbitz.com. For competing fares you can download sidestep from www.sidestep.com and it gives you a listing of all their fares alongside those from orbitz. Sometimes one is better, but usually they're pretty comparable.
Both also have listings for car rentals and hotels. Good luck
I agree w/ricegirl...Priceline rocks w/hotels! I just stayed at the Sheraton Boston on Friday for $54!! (including taxes and everything) You can't beat that... 😎