We built a cold-gas pneumatic attitude control system over the summer break and used an Arduino for running the control code. Switching to the Arduino was really a breath of fresh air, and it really improved the speed at which we could try new things. Full writeup here: Rapid-Prototyping Attitude Control System
Nice drawing. I will check out the site later.
Didn't I read that the WWII German V2 rocket used pneumatic control for their flight controls? We sure have come a long way? ;D
Lefty
On a related note - these guys:
...built these items a while back:
http://130.94.182.150/rcrock.htm
http://130.94.182.150/eyerock.htm
http://130.94.182.150/guidance.htm
I'm sure one could fit an Arduino control system in there somewhere...
Which CAD software you using if you don't mind me asking?
Wish things like Inventor or SW were affordable for a private person 
I hope you have the correct licenses and permissions to build that thing! last I heard guided missiles are covered by various international treaties 
awesome project though.
edit: Just thought id add. Inventor can be downloaded for free so long as you are a student.
I have a "legal" copy of Inventor 5 that works on my laptop, not sure if the higher versions will work...haven't actually looked at the specs mind you :-?
But I didn't know Inventor also had a free version...very very interesting and promising
I used SolidWorks for all the modeling, primarily because it's easy to make a decent model quickly with it. Also, we built this as a testing and prototyping platform--not to be used on an actual rocket (though with a little more time and cash we could definitely make it small enough to be launched).