Intel 6700 dual core
4gigs 800hz RAetc etc
FSX + Acceleration
Matrox Triple Head2Go
Everybody's addons, pay and free.
My set up is medium high in power and it runs FSX extremely well. Fast and smooth over ciites, but the sliders are not at max
Autogen is a killer, light bloom, water etc. It's all in this forum many times over, thread after thread with great leadership from NickN and others. Take the time to find and read them, your knowledge of the game and your computer will blossom.
I miss the AI density of FS9, but outside of that at medium high settings it is a delight to fly. And the scenery is significantly better with great flexibility. Addons like UTX USA and Canada are superb.
And the genuinely new aircraft like the PMDG 747 point to the next great stage in the emergence of FSX
where the scenery is not photoreal not being able to max the sliders doesn't really matter I find. If there are fewer buildings or less scenery complexity, frankly I would never know. So as long as my experience is non-stuttering, panning is smooth and the level of detail high, then in fact I can see no problems.
I have some great airplanes but I find myself flying the FSD Navajo, the plane I flew real world, over eastern Australia with absorbing pleasure - rather than developing my FMC skills on more complex aircraft. I sit there using the WAC charts and sectionals to navigate, and use clock and compass as well as raw data from VOR and NDB. It must look like I am dotty to outsiders, but it is absorbing and challenging.
FSX is a revolution - but it requires adjustment to your computer, and to you!
Do this and enjoy.