Not much of a midi guy and a guitar player to boot. With all these new Garritan toys, I want to get a basic midi controller for input of string parts etc. so I don't have to write them in note by note

Do I need much more than something like the M-Audio Keystation 61es ? What features are 'must have' ? Do I need something with aftertouch ? etc.

http://www.amazon.com/M-Audio-Keystation-61-Key-Semi-Weighted-Controller/dp/B0002H0GF0

Win 7 64, Dell XPS 17 laptop, M-Audio Fast Track Pro / Tascam US144mkII