Replying to Help editing in Premiere cs5!

Today was my first day working on cs5. I have had quite a few problems already. When I import the video into cs5, I go to play it and its all choppy and really laggy. I have tried turning the resolution down, and that has not done anything. also, when i drag it into the sequence in the top right corner, the video is shown to be really zoomed in even know im on the "fit" setting. and it is also choppy and gets stuck on frames in the sequence also. I have an HP DV7 with 4GB of ram, 500gb hard drive running 64 bit and a II dual mobile M520 processor. +++++++K for help. i dont know if this matters, but i changed the sequence to DLSR because i hear it makes it run smoother, but it doesnt work either ways.