If you're going to do rotary, you want this:
http://www.simcontrol.co.uk/newheli.htm
It's very hungry software, you need 2GB RAM, a 3GHz P4 and a decent graphics card with 128-256Mb RAM to get anything like a decent experience, whatever hardware controls you use.
I've just upgraded this weekend after trying to get it working, from 1GB to 4GB RAM and from a 128MB Graphics card to a 512Mb Geforce 7900GTX, costing about 8x the cost of the FSX software...
FS2004, the old version, works a lot better on current hardware, but the rotary experience isn't as good.
BW