Minimizing trauma for elder daughter?

I am kind of concerned about my daughter's stability when her sibling comes
along in July.

Here is the background - My husband is a resident,who will finish his
training on June 30. I'm due with the new baby at the end of July. I'm
assuming that DH will begin his new job around September 1. The deal is,
the new job is in another part of the country - new england. I'll plan to
join him around six weeks after delivery - mid to end september. So my
poor daugher will be hit with a) being taken out of her beloved day care, b)
a new baby sibling c) a move from her house, all within the same six weeks.
And every book I've read on easing the transition for the elder child
stresses keeping everything as NORMAL as possible. I'm actually concerned
that this may be seriously damaging to the poor kid.

Any suggestions as to how I can manage things a bit better? How can I best
protect my daughter? Am I overreacting to think that all of these huge
changes will be a real problem for a 20 month old?

Advice greatly appreciated.

Donna