i was wondering how much the brand of the graphics card mattered if two different cards had all the same specs. Could i just choose the card by what has the lowest price (Diamond) or best warranty (XFX)?
Most of the difference is the warranty, like others have already posted. Other than that, most of the reference cards are fairly similar. If you start getting into non-reference cards, then things start to change a bit and you have to find out how each particular design performs, but most of the brands (at least the big ones) are going to have solid performance from reference and non-reference boards.