My PC looking to upgrade replace

I am currently using this PC mainly for playing planetside 2 and when it comes to big fights the fps drops to below 24 fps and I wanted some advice about my current pc whether it is salvageable or I should do a new build altogether.

My Current specs:
AMD Phenom 9950 quad core
Centurion CPQ9104 (had to replace old board when it fried)
4 gb DDR3 1333mhz ram
nvidia gtx 280 1gb
60 gb harddive 7200rpm (where I keep game files)
180 gb hardrive 5400 rpm
psu: is good and enough to run my components, however I did make a mistake when purchasing it because it does not have a connector compatible with my gpu so I use two pci-e rails and short a circuit to get it to run.

I am not a massive expert on what games require to run however I would like to improve the fps but I do not want to throw money blindly at the problem. The two things I am looking to do are change the psu( not really sure if it will make any difference) and swap out the small hard drive for a solid state drive. Also I have questions about the motherboard quality as it was a very quick fix when my computer failed.

I look up my components on the benchmark sites and they seem pretty decent quality comparing them to some of the pcs that are currently being sold advertised as gaming pcs, I feel I should be getting higher fps or am I completely off base? Any sort of advice would be gratefully received. Many thanks.

You need to update your Video card and I recommend at least a Nvidia GTX 660, have at least 8gb of ram, get you a solid state drive to load your games from.
Your proc isn't the best, but it will surely do until you can save to replace the proc and the mobo then you can transplant that said stuff I suggested into it at a later date.

On looking at my PC in more detail I have discovered that it is infact using ddr2 ram, which my current train of thought is the cause of my lackluster performance because I have only 4gb of it and planetside 2 uses x64 bit client so more ram hungry. Sadly my processor does not support ddr3 ram which means I am a little screwed I have tried to find ddr2 ram but it mainly seems to come in 2gb sticks(although I am given to understand 4gb sticks are available). What this all means is that I am pretty much going to have to upgrade the whole lot. :15: At least thats my current thoughts.

Out of curiosity, if you did a whole new build, what is the most you're willing to spend?

Hmm not really sure, I guess between $650-$1000 or £400-600. Depends on deals and stuff like that. I will start out getting the SSD drive. See how much I got to spend at the end of month, I don't mind being paticient so I will look to do it in the next 3 months or so. Create a list of components I want and some scripts to do searches for them.

Seeing some i7 4770k asus motherboard 16gb full build deals around £400-£500 that seems to be a good price point, going further up the cpu pecking order seems to double the price. Ofcourse I will have to get a gpu also.

http://pcpartpicker.com/p/3ImOQ

Comes in at $729.22 assuming you use your current case and CD-ROM until you can afford a better case.