However, I would think long and hard about the logistics of this move. If
you are going to run Exchange and file hosting on one box, then for anything
but the smallest company this had better be a behemoth of a box. (If one
person can carry it in, it definitely ain't powerful enough to give good
performance.)
Plus, if it goes down, you'd better get the beers out as nobody will be
doing anything for a while. Having two servers (hopefully with a degree of
interchangeability) certainly aids the admin in getting a restful night's
sleep.