I just bought a Rebel XT and I am headed to NYC for a few days around Christmas and I was wondering if there is anything I should/should not do to keep my camera safe when going from outside and being cold to inside and being warm? I read in the manual that I should put the camera in an airtight bag to acclimatize it; but that seems like a hard thing to do when outside and on the move. Lets just say the temperatures are in the 30's. Has anyone had any problems with DSLR's in the past when shooting in cold conditions and coming inside and letting the camera get warm? Any tips or warnings are greatly appreciated. Thanks.