Someone (with one child) asked this on an email list i'm on  and wow, it took me back :)

i can totally relate to the "will i *ever* love anyone as much as my
  (firstborn) ds?" :)...

  i just had my seventh, and i swear it does not get old at all... i feel so
  silly, bcz of course i've had six other children, but i forgot completely
  how tiny, how dependant, how precious they are at first. My heart melts
  holding her and feeling her warm, tiny little breaths...

  I Loved being a mom when i had my first, and i was perfectly satisfied - i
  told everyone "now i've tried being pregnant and having a baby and i'm
  satisfied with what i got - maybe he'll be an only :)..."

  hm... not what God had in store - and i'm SOOOO glad - our next baby was a
  girl, sooooo cute - so sweet, so smiley - SO. MUCH. EASIER than our
  firstborn - and he LOVEd her so much, too - called her "blueberry eyes" and
  wanted to hold her all the time - it was a totally new experience, she was a
  totally different person, and it was so much fun to watch her grow...

  Anyway, yes, love doesn't get divided at all, it actually multiplies - you
  have the same amount of love for dh, ds and each child gets a whole new part
  of you that didn't exist until their birth :)... PLUS each new child has one
  more person than the last child did to celebrate their birth and LOVE
  them... This new little honey we just had in March i feel like is the most
  loved baby in the world... all her brothers and sisters just dote on her,
  and so do i...