On the F key topic, I have the same problem, when running on just one machine. I've allocated F1 to box 1 transmit and F12 to box 2. F1 just happens to be the XP Help key! It's easy to find you can't see the ground for n layers of Help screens; which is no help at all. When I remember to click the cursor on the FS9 screen, first, it doesn't happen.
Being able to disable the useless XP Help assignation would be better. Anyone know if this is possible?
When flying earlier I had the PC voice client operating on the second PC with PTT buttons operating from the first (flying) PC.
I copied the PCF client over to the second machine and gave it access rights through the firewall. It works well apart from having to manually type in the centre I am contacting - something I've been having to do since installing the PCF software anyway. It does have the advantage of not having to switch out of FS though.
I've attached a PDF "How To" for those who might like to try it. One word of warning though, it uses the WideFS keysend command which, in effect, broadcasts the keystroke on the non-flying machine. If you were to have a programme tht responds to F22 or F23 keys running on this machine then everytime you press to talk on your flying machine the function controlled by F22 or F23 would be triggered.
I've used F22 and F23 to minimise the impact. For ages I had F11 and F12 programmed on my machine but if I was browsing a web page while talking it had bizarre effects.
Needless to say, for this to work you'll need registered versions of both FSUIPC and WideFS.