Just to be on the safe side (i.e. for the next version), I would recommend:
- minimum 512 dedicated VRAM card (nvidia/ATI chipset), 1024 even better
- 4gb total RAM minimum, OS should be picked such that at least 2gb remain free for application use, i.e. by FG, some OS (notably Win7 consume TONS of RAM and leave little remaining!) - i.e. 6-8 gb total RAM recommended
- duo/quad core CPU ~ 2 ghz (i7, 8-core, recommended)
If you want things to be really fast, get a SSD hard disk, too
Those may seem like "extreme" recommendations, but truth be spoken: If you decide to get a computer with such (or similar) specs now, you are unlikely to have to upgrade anytime soon (even if it's a notebook!), certainly in the context of CPU power.
The FlightGear architecture is still such that it isn't very good at using all the hardware power that's commonly available today, especially in the context of multicore platforms:
viewtopic.php?f=17&t=9315&p=93556&hilit=#p92954In fact, I haven't seen any significant FG performance improvements in quite a while,except of course in the graphics department (i.e. shaders). X-Plane is still much better at making use of idle cores than FlightGear currently. So it is pretty safe to say that modern hardware that you buy these days is going to remain usable for future FlightGear versions. OpenGL and shaders are probably going to be the limiting factors here, because FlightGear is making increasing use of these features these days.
BTW: I recently updated the hardware recommendations here:
http://wiki.flightgear.org/FlightGear_H ... mendations