Really need some help with a GPU Upgrade

[MrElve]

Okay so I recently have got myself back into gaming on my pc for a bit as xbox is starting to get a bit boring now with all the 10th prestige little 5 year old kids who mod etc.. and I really really want a graphics card upgrade but I dont know if my pc could handle it

Here are my specs:
CPU: AMD Athlon II 64 X2 Dual Core 2.7Ghz
RAM: DDR2 4GB Dual Channel @ 800Mhz
PSU: 350w (stock)
GPU: Zotac GeForce 9500 GT
HDD: 300GB SATA
Optical: DVD-RW 22x (i think)
Motherboard: FOXCONN A74MX-S/A74MX-K DDR2

Now I do have a PCI-Express x16 on this motherboard and I was thinking of upgrading to maybe an ATI Radeon HD 5570 but im unsure if wether or not it will be much of an improvement to the graphics card I have at the moment

Im willing to spend anything up to £90 for a decent upgrade to help me play games higher than low quality , (i.e. Battlefield bad company 2, just cause 2, etc..)

If anybody else could suggest me a GPU please do.

I have also been told that I should upgrade to maybe a 400-500W PSU but some people also said its not necessary unless you upgrade to a big hungry GPU.

all help is greatly appreciated,
Danny.

EDIT: Wether this will help or not, I run on a 19" @ 1440 x 900, just incase it helps..

 

[MrElve]

Yeah..

It's not a dell, its made by somebody else but i didnt want to say because you're not supposed to really say another manufacturer on a different manufacturer's forum

Idk if the PSU is good or not, all i know is it's a 350W =\

Im probably just thinking of building a custom gaming PC at Christmas because my family said if i wanted one really badly they would all chip in for me and give me a budget of £750 ish soo.. yeah

oh and by the way, whats so good about 4850/4870/4890's? i look at 5500's etc. and they are cheaper than the 4800's!!! plus people have maxed out crysis on a 4870 and not a 5500?? i thought the 5500 was a better model because its a higher number? =\

I'll post specs of a build im thinking of in a moment, im just finishing it off then maybe i could get some comments?

 

[MrElve]

Ok how about this?

Watercooling is for if i maybe decide to overclock to 4Ghz, still unsure and trying to find tests :/

 

[MrElve]

5750 is a little bit out of budget, around £100 ish.. what about the 5570 i suggested earlier or would it be worse or only a tiny change or no change at all?

plus the 5750 would work on my motherboard without spending another 60-70 quid on a new PSU because it requires 2 X 75Watt 6-pin, i dont have that on my PSU... remember its a 350W ATX, it doesnt have PCI pins, to run the 5750 you would want at least 450W minimum..