Will my PC run CoD?

[Stormrider]

I started with a AMD phenom xII 945 (4x3.00ghz) and with 4GB ram and a radeon HD5850 1GB video card.
On my rig it didn't run to wel, so I decided to look for another video card.I found a radeon HD6950 with 2GB.But... it didn't work on my motherboard.This is something what makes it so difficult to give people good advice.Iam afraid that if you choose to upgrade your video card you also get that problem or other problems.
If you want to fly, why don't you look for Il2 1946?That game you can play without a problem on your rig.And maybe in future you will have money to make a serious upgrade of you pc and buy a game like clod and realy enjoy the graphics of it.