I feel I should mention that I've had my Yamaha CS6x synth for about 3 years now and will NEVER sell it. For me, it has a fantastic mix of modern synth sounds and some nice acoustic stuff as well. It take Yamaha PLG expansion boards so you can always add the VL, DX, AN, etc boards for even more sounds.
http://www.planet-groove.com/yamaha/cs6x.html

Carrie