I should probably add that a head tracking device is
very recommended. There are several options available. I use TrackIR5 and at $150.00 USD, it probably tips the scales in head tracking cost. If that is out of budget, there are other options, like Free Track (IIRC) etc. which usually involve a web cam or PS3 eye. Not hard to find if you do a internet search.
Switching from a Joystick to a
HOTAS was a huge boost in immersion, but having a head tracking device was even better.
If I had to give one up, I would keep the head tracking.
-schnidrman