There are quite a few things you will want to keep in mind when purchasing a new graphics card. You already have your budget nailed down, which is good. That is where I usually falter. Next, you'll want to look at the actual GPU, and the amount of memory it has. For your budget, you will mostly come across HD 7790 - 7750 cards when it comes to AMD, and GTX 650's for NVIDIA. All of the ones I found had 1G of gddr5 memory, which is the standard, so you should be good to go there. You don't want a card with less than that, or without any dedicated memory at all. Honestly, you pay for what you get when it comes to graphics cards, so choose wisely, and be sure to look at reviews. In my experience, Asus is the absolute best when it comes to basically everything, but EVGA and Zotac have never done me wrong. I can't really speak from experience with any other companies, for I have always just stuck to Asus, although, I have friends who have had good luck with MSI as well. You will want to check with the specs of each card to make sure it will work with your particular board, and that the drivers will work with your operating system. Size will also be a bit of an issue, but you will just have to check to see how much empty space your case has.