Computer Upgrages for Arma 3

[BlueCopper]

I've got a HP Envy 1534 that I purchased new about a year ago. It has no modifications done to it as I really have no clue when it comes to computers. I recently got into Arma 3 and I'm looking to run at higher graphics settings while still getting good FPS. Can anyone tell me what the best upgrade to the computer would be? I'm guessing the graphics card but I don't know that for sure and I don't want to waste money on something I don't need. My budget is limited. Thank you in advance for your help.

 

[BlueCopper]

Sorry I should post the specs so you guys don't have to look it up.

AMD six core GX-6200 Processor
10gb DDR3 system memory
1.5 TB hard drive
AMD Radeon HD 7570 graphics card

I believe I read that the power supply is 460 watts.