I personally chose a Casio CTK-5000 as my first keyboard. Bought it over a year ago and am still learning all it can do.
However, if I were to buy one today? Their new CTK-6000 and CTK-7000 models are out, which now include a full tone editor (attack, sustain, decay, release, etc.) and I would jump on one of those in a heartbeat.
They are just now starting to be seen in stores with the CTK-6000 having an introductory price here in the USA of only $200. A phenomenal deal.
http://www.casio-intl.com/emi/high_grade/ctk6000.html
The CTK-7000 is even nicer (better pattern-sequencer editor, drawbar organ slides, full-fledged audio recording, etc.), but then you're jumping up to about $350.
Then again, I'm not you so you might also want to look at boards in their WK lineup. (CTK = 61 keys, WK = 76 keys = higher price, e.g. WK-6500 ~US$300)
I'd strongly suggest downloading a manual of any keyboard your are seriously considering.
http://support.casio.com/manuallist.php?rgn=5&cid=008 To make sure it will do what you need.
That's how I shop online, for most anything. General research > download manuals of items now on the short list > choose one > find best deal.
(Interesting, I just noticed the CTK-6000 has 670 tones, 200 rhythms built in (503 more if you download casio's freebies, see another post of mine). Same as my 5000. I bet the 6000 can use the very same Cakewalk "Instrument Definition" file I just created for the CTK-5000. That'd be cool for new owners of them. Just a few extra controller names would have to be added for the new features. I'll have to read their manuals now, I'm curious.)