It was probably this page:
http://www.hammerzone.com/archives/d...hang/solid.htm


Or another page at that same site. Anyway, having done this 3 times
recently, I found that measuring the existing jamb to be more accurate
because your matching up method assumes that the existing hinges on the
door are on the right spot. In my case one of them was 1/8" off! I
corrected that on the new door and when I went to hang it it matched up
perfectly! And it was a heavy exterior door with 3 hinges on it, and
believe me, that makes a difference. I caught the previous
misalignment by attaching my new hinges to the existing door and jamb
and tried to rehang it, just for test purposes. When I backchecked
everything I discovered that there really was one hinge that was off by
that much!