I would also recommend Casio PX330 or PX3 as excellent choice as they both have fully weighted hammer action keyboards. I am a professional pianist brought up on real acoustic pianos and can say that these reasonably-priced Casio models are surprisingly good to play and close to a genuine grand piano action. The Casio WK7500 (I think that's the correct model number) is fantastic with excellent sounds and features but it does not have a keyboard action for serious piano playing. The PX-3 is more of a stage piano and does not have built-in speakers or auto-accompaniment features. The PX330, on the other hand, does have built-in speakers and can do auto-accompaniments. The acoustic pianos sounds are excellent and electric pianos pretty good although some of the many other sounds included are variable. The speakers on the PX330 are small and amplification is quite basic so it sounds much better through larger speakers.

I have a PX-3 and it is brilliant to have a fine gigging piano with proper 88-note hammer action keyboard which you can pick up and carry under one arm!! Casio keybaords are very easy to link up to a computer and you do not need to download or install any drivers for either PC or Apple.

Anyway good luck with your searches.

www.tonycliffmusic.com
http://tonycliff.bandcamp.com