FSX is rather CPU dependant. The core 2 quad is much better.
However, because it only has integrated graphics, I doubt the game would even run in anything but absolutely minimum settings. Therefore, despite the CPU deficiency, the Phenom system would perform better for FSX.
However, you could purchase the first system and add in a radeon 4650 for about $60 and it would own the phenom.
If you really don't want to spend even that $10 more for a 4650, then consider under $50 cards like the radeon 4350, 9400GT, Geforce 210, 8500GT, radeon 3650, radeon 4550 etc. The 4650 would be worth it though.