yes - i know exactly how u feel.
that happened with me with some videotapes..
i was never one for the workout tapes; i always was a treadmill girl ..
until recently, i started gettin into different workouts and strength training. anyways, i was sore the first week too but i was just like you - i could see a difference by the 5th day. altho after that first power week of working out to those tapes, i have kinda been bad and slipped off my routine
but yea ...dont fret ..it's a good sign
keep it up!