naddie,
give it a try, and depending on how adventurous you are, again I would suggest going to the trouble of pulling the mb(Youre never gonna be sure that your didnt smear the hs paste or not get the hsf centerd )with the mb in the case.
As for the fan, not really, tower sits beside the disk, 18" off the floor, I have to listen to hear any of the fans, and with background stereo, tv or something allways on it's not a problem for me.