I'd also say get something with speakers and built in sounds. As Eddie pointed out, you can always turn the volume down.

My advice would be to get at least a 61 key synth. Midi out can be either midi port or USB. And weighted or unweighted keys depends on you. I prefer the weighted keys because I was a piano player and piano's have weighted keys. Also you might wish to consider touch sensitive keys. The harder you press, the louder the initial note, again, just like a real piano.

And yes, the Casio brand has come a very long way from the cheap sounding stuff they were known for years ago.

I have a Yamaha DX-27S and something from radio shack that was given to me. The DX-27 is my standard piano here.... non weighted, non touch sensitive. Go figure.

You can find my music at:
www.herbhartley.com
Add nothing that adds nothing to the music.
You can make excuses or you can make progress but not both.

The magic you are looking for is in the work you are avoiding.