I have a HP compaq 6005 pro sff with a ATI Radeon HD 4200 graphics card in it, AMD Athlon ll x2 3.0 ghz processor and a 240 watt ps. I wanted to upgrade so that I could play WOW without all the lag. I have it on the lowest setting and only get about 9-14 fps. I was looking at a XFX HD 6670 650MHz 2GB DDR3/HDMI/DVI/VGA PCI-Express Graphics Card HD667XCLF3 on amazon, most of the reviews say it will work with the ps that I have. I don't know much about it, just wanted to know if this would work on my computer and if it would be a good upgrade for what I am wanting it for?