Inspiron 530 graphics card suggestions

[jamesenterprize]

I am looking to upgrade My Dell Inspiron 530. I am upgrading the CPU from a Pentium(R) Dual-Core E5200 @ 2.50GHz to a Wolfdale Core 2 Duo E8400 3.0GHz 6MB 1333FSB 65W E0. Now I am wondering what would be the best gaming graphic card for this Inspiron 530. I currently have a NVIDIA Geforce 8400 GS ( good graphics)...but I am looking for better graphics! So What Is The best Graphic Card I can get for this system. Without changing my psu!

 

[king smp]

without a doubt I would recommend a HD 5670 or HD 6670
without changing PSUs those are the best cards to my knowledge
I have a HD 5670 in my Dell Optiplex 745 (sister tower to Inspiron 530)
running on a 280w PSU
it will handle 1920x1080 resolution with some settings turned down
for example here is my rig running Crysis 2 at 1920x1080 DX9 Hardcore setting
http://www.youtube.com/watch?v=BqoFA9Q5zSc

Also a GT 545 maybe an option though I havent checked PSU requirements