From talking with my DH last night, it can be really difficult for men to adjust to the big change - harder than it is for us girls. He said that when we first had DS he felt really left out of the big picture, all attention being focused on the bub you know? But he got over it, and said that it helped to be able to feed the baby (I bottle fed which made it easier to do that!). But still, he always felt slightly useless and not needed, which can lead to arguments. I think just being aware that some men go through these feelings can help heaps.
We still have arguments now of course, mostly when we are tired, and he does something stupid, and I'm a biatch about it because I'm tired, and pregnancy hormones don't help - but for the most part - when DS does something funny or cute, its always DH that I look at and laugh with.
As long as you still keep on laughing, I think you will all do fine.
Lots of hugs help too ...