According to the online System Requirements Lab I can not only run but play FSX. All of the statistics show that my system is more than capable of running FSX. My specs are:
Windows XP Media Center 2005 SP2
Pentium 4 3.2GHz Hyper-Threading
1GB RAM
GeForce 8800 GTS 320MB
SO what do you think. Dd you trust the Lab? Can I really play it?
I have the same hardware, excepted that your video card is much more powerfull than mine (I have a 6800 GT)
I could play it before SP1, and with SP1 it's even better.
The only problems:
- 1 Gb of RAM is a bit limited, so you get a lot of micro stutters because of disk activity, and longer loading times
- the proc is not powerfull enough to build the scenery. It's OK when you fly a little GA aircraft at slow speed (less than 150 knots), but if you go too fast, you will get blurries on the ground and the autogen will popup very near to the plane.
Other than that, I can really ENJOY it, not just watch a slide show, see what I mean ? For now, I cannot enjoy a real flight with a liner or a fighter plane, because of the problems written above, but I really get a lot of pleasure and fun flying those slow aircraft (GA and gliders) across the beautifull default and non-default FSX scenery

But WARNING: tweaking FSX is MANDATORY.