Help with a decent build

[MrDangDeal]

Hey Everyone I need help beefing up a somewhat lacking basic pc. About a year ago I purchased a Hpe H8-1234 Desktop made by HP. At the time it met all my needs as a basic functioning computer used for little effort rendering and editing. However I have been growing much more fond of PC gaming lately especially with the approach of the next gen consoles looming ahead. I know I would rather enjoy gaming with a pc then waist money on another console that will just fall behind in no time. So anyway I know its not a great idea to try to upgrade models of these standard pc's but like I said I have never been a hardcore gamer.. not yet.
What I have.
:HP Pavilion HPE h8-1234 Desktop PC AMD FX-Series FX-6120(3.5GHz) 10GB DDR3 AMD Radeon HD 7450 Windows 7 Home Premium 64-Bit terrible HDD.
What I am looking for is the parts needed that I could potentially add to what I have in order to run games such as Battlefield 3. So What graphics cards and power supply's would you guys recommend also I don't know much about mother boards so if someone could let me know as to whether or not I can use the one built in this pc I would appreciate it.

 

[montosaurous]

What is your budget? The CPU is fine I guess, for now.

 

[Mousemonkey]

This topic has been moved from the section CPU & Components to section Systems by Mousemonkey