FSX like any game, is highly dependent on the graphics card. Get a good video card. 7600GT is not enough. 7900GS is the slowest video card I would even consider buying. If you are serious about running FSX you need something faster like a 7950GT or X1900XT.
You also may want to save some money by going with E6600 instead of E6700. E6700 costs $200 than E6600 and is only 260 mhz faster. The cores are the same, E6700 just has a higher multiplier. Save $200 and go with E6600.
A 10,000 rpm drive is nice, but I wouldn't call it essential.
For motherboard I think the Gigabyte GA-965P-DS3 is a good starting point. It is a solid board and a great overclocker at a low price. If you want SLI or other extras you can go from there.
The speed of the memory matters too. PC2 6400 is the standard. A lot of builders use slower PC2 5300.
It sounds like an OEM system because they stick a powerful CPU on a slow video card. If you are buying OEM you should check the prices of individual parts to see if you are getting good value.
When buying/building a system the best thing to do is read hardware reviews so you know what you're getting. You might want to check out HardOCP since they benchmark OEM systems and video cards using FSX.
http://www.hardocp.com
Last edited by cheesegrater on Sat Dec 09, 2006 9:20 pm, edited 1 time in total.