That $400 card is a special multimonitor card with six mini DisplayPort connections. The other two cards are slightly different, the more expensive of the two is factory overclocked with additional cooling, the less expensive card is a reference design. As for brands, I usually go for XFX when it comes to AMD cards due to their warranty. When comparing the GTX 570 to the 7870, the 7870 is a little more powerful. As for whether or not it is worth it, depends on your cash on hand, along with your personal preference. 60 frames per second is the sweet spot for most gamers.