I agree that 50 minutes is not enough time--it usually takes me 20 minutes to get through immigration and customs--however, last time coming in from LGW to IAH (and fortunately in BF), it took almost 35 minutes and I was #8 in line--I felt sorry for the poor guys in the back who probably had an hour wait at best.

I guess the good thing is that we didn't have to then wait for the luggage to come off the carousel.

Since you do come in at the International Terminal (Terminal D), you then must transit over to Terminal C to catch your flight to Steamboat--this will take you 10-15 minutes most likely.

Good luck on your trip. Steamboat is an awesome place to ski!!! I love it--have been there several times and will definitely go back--maybe even next spring as well!