On a desktop, having AMD is fine. Pricewise it's usually better, and upgradeability is great. AMD rarely changes sockets, so if he felt like it he could currently go as high as the top of the line AMD 6 core processor.
On that note, check out PC Perspective's Hardware Leaderboard, specifically the
budget system. They try to get the best performance for ~$500, but also have more expensive builds for a midrange system for ~$900, a high end system for double that, and a dream system for just over $3000.
At any rate, they have a $200 card in the Midrange system, and a $86 card in the budget system, though they do mention a great GDDR5 based card for ~$125.