You have a point.
But i believe they do this because Nvidia and ATI cards aren't released in pairs. There isn't always an exact equivalent.
So instead they list the more common card and you can do a quick google search to see how they compare.
Nvidia cards
http://www.hardwaresecrets.com/article/132
ATI cards
http://www.hardwaresecrets.com/article/131
I'm not too knowledgeable when it comes to graphics cards and their functions, but after having a quick look at the above i think you'll need a Radeon X1800 XT or better. But as i said, google always has the answer.
