I just came into Dulles from Europe this week. Even if you fly into the new terminal -- which doesn't have passport control and immigration -- they move you over into that area fairly quickly. We got through everything, at the busy time at day, in 40 minutes, and you have much more time than that. You'll be fine.
"Youth and vigor is no match for age and deceit." -- Prancer
For those who frequently use Orbitz-
How difficult is it to get a flght route changed after purchasing the ticket? Mine is a nonrefundable and nonchangeable ticket. Does it mean it is absolutely impossible to get it changed (or deleted, and replaced by another ticket)?
No, just call the airline. It's going to cost you, though.