USB Keyboard or Keyboard Controller

[anemone]

I've been long planning to make my own music, and decided I would work with a keyboard before I work with a guitar. What I plan to start with is a DVD I found online with complete WAV samples of different pianos and organs, to use through Reason or Pro Tools LE, depending on which one I decide on. The purpose is to "have" a Hammond B3, through a keyboard, to start recording my ideas.

However, I have no idea whether to buy a USB keyboard, like a 61 key Yamaha with all the pre-loaded beats, instruments, etc. that I have no interest in using, or a keyboard controller, like a 49 key CME U-key. I understand that it's at least partly a decision between playing without a computer if I want to, or exclusively with a computer, but I'm also wondering about the possibilities between each. It's also sort of a question about how these things work in general. Would the Yamaha type work the same way as a controller in those programs, assigning any sound, note, etc. to any key?

My end interest would be the ability to use those programs and the keyboard to create all manner of atmospheric, beat, etc. sounds, as well as a natural organ or piano setup.

Apologies for sounding scattered.