Re: help me in buying new graphics card..
You can go for the 9800GT Green edition if you dont want to change your PSU. Or go for the 4670 @ 4.5k for the 1gb edition. I had one and could play all games except crysis (which i played all high @ 1280x960) @ 1440x900. I used that on a stock PSU along with an AMD X2 4400+ @ 2.31Ghz had no bottleneck or anything as such. It did a decent 50+ fps in farcry 2 with very high settings @ 1440x900. So you can see the card is good. However as most of the others would say on this forum wait a while and get the 5670 @ around 6.5K with dx11. Upto you man. Btw for a standard 9800GT you will need to change your psu if you don't have a proper one.
Your CPU may bottleneck any card!!!!Change it!!!