I wouldn't rent the card if I were you. For the price they are asking, you would have paid off the card after renting it for 10 months. Check out this sites. Tom's hardware makes a report of what is good at every price point.
http://www.tomshardware.com/reviews/gaming-graphics-radeon-hd-6870-radeon-hd-6850,2782.htmlIt's rare though that reviewers make benchmark reports for sports games, check out this link, perhaps the game you want to play is here.
http://www.tomshardware.com/charts/2010-gaming-graphics-charts-high-quality/benchmarks,114.htmlThings to consider:
1. How much is your budget? Right now I suggest you spend around $150, for that amount you can get a card that will perform well for full HD resolution (1920x1080). You can check from the chart that it should be able to play at 60 fps.
2. Card features, Does it have the display port you want? HDMI, DVI or just plain old VGA.
3. DirectX features, though maybe not as important to a casual gamer. DX10 is good enough, but I've been trying out DX11 lately, and it looks really good.
So if I were purchasing a card right now, I'd probably want an ATI 6850 or nVidia 460.