Michael, thank you. What would you recommend in terms of hardware for 2004?
Decide what's the best you can afford and then sell one of the kids and improve on that and you should be all set. (jk) ;D

Seriously, I wouldn't recommend anything less than a 2 Ghz processor and a gigabyte of RAM. I haven't tested it personally but from what I hear the bus speed is key to good performance so make sure you get a good MB that supports at least 800 Mhz FSB or better and don't get anything integrated.
Some people get decent performance on lesser systems but that's hit and miss. I'm running it on a somewhat marginal system and just barely making out. (AMD 1.8 Ghz processor, GForce 4 128 Mb. I Gb of PC 133 RAM). I can fly out in the boonies pretty well but dense scenery, clouds and AI takes the breath away from my little machine pretty quick.
One thing I have to give Fs9 though, it's a hell of a sim if your machine can handle it. Much improvement over 2002 but you pay a price for the goodies ($$$).