Windows 7 - Graphics Card Recommendations

Hey,
I have been looking to get a new graphics card lately as my current one is starting to lack power for modern games. I was just wondering if you can give me some recommendations of some good graphics card that can be covered by my current power supply (620W) and rig ( see details) or if you know a good power supply calculator that I can look into so I can check what I can take.

I am also not looking to spend a lot of money as if that was the case I would probably just buy a new computer. My budget probably be anywhere from $100 - $300, or that is the amount I am willing to pay.

Any help would be appreciated.

Rig Details:
CPUMotherboardGraphicsRAMPhenom II x 4 955 Gigabyte GA-MA790XT-UD4P ATI Radeon 4870 4GB Corsair DDR3 Hard DriveOSMonitorPowerSeagate ST3500418AS 500GB Windows 7 Home Premium BenQ G2420HD Corsair 620HX CaseCM 690

PS: Did some research and narrowed it down to these 2 :

HIS Radeon HD 6950
HIS Radeon HD6950 1GB IceQ [HIS-6950-1GBD5-IQ] - $239.00 : PC Case Gear

or

Sapphire Radeon HD 6870.
Sapphire Radeon HD6870 1GB [11179-09-41G] [SA-6870-1GD5] - $195.00 : PC Case Gear

id go for the XFX 6950 2gb card i did.. and have 0 complaints!

well I don't really want to spend around $300 and I don't really think that I need the 2GB version as I only have 1920x1080 max resolution

i only have a resolution of 1920x1080p, and im not sure if the 1gb would cope with the likes of bf3 maxed out. ive had as low as 35fps at some points on bf3

I can run BF3 maxed out at 1920x1080 on a single monitor with a GTX570 with 1280MB of video RAM. I don't really think 2GB is necessary.

All depends on what game(s) you're playing. This is from BF3 with most settings on high and no AA, running at only 1680x1050,



Getting close to the 1 GB on my 6850.

anyone know any good sites where I can check benchmarks between the 6850, 6870 and 6950?

toms hardware is usually quite good, Test Setup And Benchmarks : Radeon HD 6970 And 6950 Review: Is Cayman A Gator Or A Crock? quite a few benchmarked on this test.