Firstly, no one can say what settings will definitely work for you. I would say that sliders all on ultra high will slow down your rig, not many can handle full FSX yet.
If you have an nVidia card, download nHancer from here:
http://www.nhancer.com It is a tweak utility for the nHancer cards that does wonders! In it there is a unique option called "Enhance in game AA" which basically means you turn the AA option on in the game, but nHancer chooses which level of AA to use.
A good set up for an nVidia card is under AA select"Combined" then 8xS, put a check inside "Enhance in game AA" and a check in "Gamma Correction"
For AA I'ld set it to 16x
Under the optimisations tab set the Texture filtering to high quality and negative LOD Bias to Clamp
Under the Compatibility Tab turn HDR on and if running XP select Single Core under CPU multi core support or under Vista (even with 1 core) or Dual Core select Multi Core
In FSX, under display turn filtering to anisotropic, and put a tick in AA. All the other tabs play with yourself til you find settings that suit you.
