My ATI 5850 has gone faulty i'm looking for a cheap replacement. As of now I only use my system for designing, video editing and watching HD content. Since my Card is out of warranty, I don't want to spend that much on a card [max probably around £100]
MOBO - Gigabyte H55M-UD2H
CPU - Intel i3
RAM - Corsair XMS3 2x4GBS
CPU - Corsair TX 650 - PSU
DISPLAY - ASUS IPS Panel (1920x1080) + (1440x900) LCD
OS - Windows 7 64BIT
The 560 is faster from these 2 cards and will have around the same performance compared to your old 5850 card. 6450 will lag on designing 3D, and edit HD videos. 560 would be a nice futureproof card. Another option is the 6870.