Questions on upgrading my '08 era PC

[kooj]

I bought my '08 PC from a friend of mine as is and I am looking to upgrade it play the latest games smoothly(especially BF3, kills my PC everytime):

* Zotac GTX 260(Stock)
* Asus P5N-e Sli mobo
* Intel Quadcore Q9300(Stock)
* COOLER MASTER eXtreme Power RP-550-PCAR 550W ATX
* 4 Gigs kingston DDR2(800)
* 500 GB HDD
* Prism Multimedia Case(old PC case with only 1 exhaust fan)<Sucks during summer

I don't really have a fixed budget(planning to round it off at $400~), so I am not looking for anything too overkill, this what I came up with

* Corsair 500R White $109.99

* [MSI Radeon 7950 TF3] $309.99

* [Cooler Master Hyper 212 EVO] ($30) [OC my CPU?]

Any suggestions? thoughts/ideas I should look into? I am still reading up various resources and guide to get a better understanding of what I need to look out for, so I am still a newbie at this unfortunately

I plan to eventually upgrade my mobo/cpu later as well

Edit: A quick question, I have 2 PCI-e cables from my PSU, however, one connector is 6 pin, and one is 5 pin, will there be problems when I connect to the latest GPU?, my GTX 260 requires two 6 pins, and it still works with 6pin and 5pin connector from my PSU

 

[geofelt]

A 7950 needs a 500w psu according to AMD:
http://www.amd.com/US/PRODUCTS/DESKTOP/GRAPHICS/7000/7950/Pages/radeon-7950.aspx#/2

However, your psu may not be adequate. It is a tier 4 unit on this list, only being able to deliver 75% of advertised power.
http://www.eggxpert.com/forums/thread/323050.aspx

I love the looks of the corsair 500r, particularly white. It looks huge, and is about twice the cost of an equally functional case.
But, if you love it, buy it. Cases are a personal thing.

I suspect that you will have to OC your Q9300 to get better gaming.

You might want to run this test:
Run your games, but lower your resolution and eye candy.
If your FPS increases, it indicates that your cpu is strong enough to drive a better graphics configuration.

The GTX260 is still a very good card. If your fps does not improve, perhaps a cpu upgrade first may be in order.
You might want to buy the cooler first and experiment with overclocking first.