Second everything Panther said.
Hitiles and Ayes' 1920 x 1200 res pits are brilliant, and excellent value for money.
I'm running on Win 7 64 with an ATI card, and it runs perfectly. Trackir works great, but in 2dof.
If you look around here: http://tactical.nekromantix.com/forum/viewforum.php?f=48
you'll find several theatres, some of which also support Allied Force, but I've never tried any of those since the Korean and Balkans theatres have been more than a handful and I'm still working my way through them
This site has additional skins, hi-res explosions and sounds updates: http://combatace.com/files/category/128-falcon-40-allied-force-by-microprose/
, although I use Gunny's sound pack that Panther mentioned because it rocks so hard! I haven't bothered with skins myself, as I hardly have much time to look at pretty paint jobs when I'm flying AF. Seems I'm always busy trying to NOT get blown to pieces while managing my pit and flipping through the manual trying to figure out how the heck to engage NWS (an old Falcon joke).
And I second Mig's post about tweaking some settings. As said, it works fine out the box, but with some tweaks you can improve a lot of areas, such as terrain resolution, certain cockpit behaviours, etc. These forums have a wealth of info on this stuff, and some really helpful veterans to boot!
Happy flying! Once you get into it, you'll never want to leave