First of all, this should be posted in the hardware section of the forum.

Back to the subject. You can get a decent card for under $200, which will play FSX just fine.

Here's one which I recommend: http://www.newegg.com/Product/Product.aspx?Item=N82E16814130840

If you play games which require more graphics power (BF3, MW3, Crysis, Skyrim etc), then you should buy something like this: http://www.newegg.com/Product/Product.aspx?Item=N82E16814130810