Well thats the golden question.Honestly it could run fsx? yes.Now in terms of high or low graphs.
Low, to be honest, thats a machine you could use for fs 2002 or fs 2004.
Besides many other things, i can tell you.
Memory ---- 6 gb and depending on the cilc.
2.5 ghz dual ---- noooo
500gb at 5200 rpm not even if they were 3tb... slow.
and ofcourse many things missing. Nvidia card---- what card?
PSU?
Im sorry if you were expecting some other answer but the fact is, we are talking about what $600 or maybe $800 machine? Even i guess its to much.
Just take a look on the forums about FSX and requirements and hardware that guys with super machines have.
if you want to keep that machine, try to improve for fs9
TC