If your going to spend that much money on a gaming keyboard you should consider this, in combination with a regular keyboard.
http://www.twitchguru.com/2005/03/08/the_dx1/
http://www.ergodex.com/mainpage.htm
I used this for wow and wouldnt go back, I had about 20 keys mapped onto it in the natural shape of my hand by the time I was done.
It does loads of other stuff I never even used like timed macros and things, mostly because they were against the wow T&Cs.
I've also tried this on FPS games with equally satisfying results, I cant say it made me any better at them, but it was a lot more comfortable for prolonged play, no more hand cramp.
upsides
* you can map all of the keys to anything you want
* you can position them where ever you like on the device
consequently it doesnt make any assumptions about the size of your hands so it you have long short or fat fingers it doesnt matter.
downsides
* its a bit hard to get outside the states, I found one shop in the uk which would import it.
* vista support isnt there yet, although its announced as being worked on, new drivers dont seem to be their No1 priority.