randoker - just had a chance to read this thread. Good luck with the new addition - is this your first?
Yes to the A90 running a piano VST but for right now for $1000 - I'm thinking you're going to be very busy very soon - why not think about a switch it on and play solution to keep you going - for those occasions where you're only getting a few minutes to yourself. You'll not want to be waiting for a computer to power up, and tweaking buffers, and tracking down rice crispie crackling noises, and selecting options ...
If it's just to be set up at home - for playing piano - and you're ok to run it through a set of powered monitors (active nearfields?) as you mentioned in your original post:
http://www.keyboardmag.com/article/Casio-Privia-PX-3/2319
That's a link to the Keyboard (US) magazine review of the Casio PX-3. I got a chance to play one a few months back. It's a good buy.
Also you could search for a second hand pair of active nearfields like Tannoy Reveal 5As or ... lots of good stuff available now. The (UK) magazine Sound On Sound has plenty of reviews. A Paul White review (IMO) is something you can take as being reliable and fair. Plenty of other reviewers on there that I like (Dave Stewart - the prog rock one, not the Annie Lennox bloke) is good for keyboards and VSTs/samples.
http://www.soundonsound.com/search?url=/search&Section=7&Subject=42&Summary=Yes
That's the link (I hope) to the "monitors" section of the reviews. If anyone is reading this a while from now (and it has changed) do a search for SoundOnSound then the "Articles" tab followed by "Reviews" and "Monitors."
Active Nearfield Monitors.
Loads of them about.
Hopefully that should bring you in around the $1000.
And again - good luck. People kept telling me that "your life will change forever." Then one mum new said - it would be more accurate to say "your time will never be your own."
My brother in law reminded me of the language tapes I bought in advance "for learning Spanish during the night when I'm up doing the feeds, just to make good use of that time, if I'm up doing feeds anyway I might as well do something useful at the same time" - he's right, I'd no idea what was on its way.
Be sure and let us know about any new additions - keyboards and ....