I asked a similar question the other day with a budget of around £500 and havent had a response yet (possibly my fault for not being specific enough) so thought I'd share a few things I've learned while looking for mine.
These are some comparison charts you can look up the model of the gpu/cpu to see how they rank against each other. click here some graphics cards dont appear on that list (or only appear as a dual graphics test), so I found this other site that will give you models that compare to them in performance (which you will be able to look up and therefore get an idea where the actual gpu ranks), it should also tell you what kind of settings it should handle for what types of games: click here processor in the first one looks to be about half as good as the one in the second one. Graphics card in the first one looks to be about 33% better than the second.
Personally, I'd go with the second one. I didnt look up all system specs though so you may want to double check those.