Controller recommendation please...

Hello all, I'm looking for a simple midi controller that I can place on my desktop. Yes, I am stuck way back in time. I've never used one because I have been recording live instruments. I have Pro Tools MP 8. Currently I only record MIDI for piano sounds and I am currently using a mid 80's Roland 88-key stage piano as a controller with piano and synth plugins. I have been using a Alesis drum machine for backing tracks, but it has stopped working. I think I'll try creating backing track with plugins, so I've been looking at the M-Audio Axiom Air mini 32. Will this controller work ok with PT 8? Also, I want to be sure that adding another controller doesn't mess with the functionality of my current midi controller. I also like the looks of the Samson Graphite M25. I just need something inexpensive to play around with for now and see if I like it. Thanks for any advice.