Help on choosing digital keyboards(piano)?

This would be a midi keyboard, has a midi output, to plug into the computer midi in. After that, the sound comes from the computer, not the keyboard. The keyboard is just a controller.
If the computer does not have a midi input, you can buy a card with a midi input, or an external midi input that plugs in to the usb.
The best bet is to go to your local music store and try different midi keyboards. Pretty much all of them have touch control sensitivity. You can just buy the keyboard with no sounds. Some you can wear around your neck, some have a stand, some are 88 keys, depends on the budget.
I like the yamaha midi keyboards, which are easier to get parts and service for.

Yamahas Like The PSR-E series? The PSR-E223 below budget but does not have touch sensitivity while the PSR-E323 does but its alittle off budget. Also not sure if it has tones of all different instruments

Thought I would ad a few things to this post, I have an EMU X-board 61, and have been very happy with it, it also has the option to connect via USB, which can be convenient if you don't have a Midi input on your sound-card, or maybe you want to use that for something else. The X-Board has adjustable velocity curves, you can also create zones, and, it has 16 rotary knobs which you can use to control parameters on your computer, like synth or DAW functions. I have tried most of the popular computer Midi keyboards, and this one has the best action in my opinion, I used to own a Yamaha DX7, which was recognized as having one of the best actions of any keyboard, a sort of industry standard, the X-Board comes very close, that's why I bought it. It also falls within your budget, plus you get the Proteus VX sampler bundled with it, plus lots of sounds, like "Planet Earth" Mo'Phat" and "Protean Drums' make sure you get these with it if you decide to buy one. I know keyboard action is a personal thing, but try it out, at least. This keyboard also has wheels for pitch and modulation, which are far better than those awful levers that you get on some keyboards

http://www.emu.com/products/product.asp?category=532&su...

PP.