VIdeo Cards

[Trunks]

Yeah, it's pretty difficult to tell which cards are better. Graphics cards are also the single most important thing for gaming. You have to look at the spec's, not just how many Gigs the card says or the newer model number. Memory bandwidth and memory clock speed are for running higher resolutions and multiple displays. Texture units for tf and af during gaming helps keep the from being choppy and processes information. The rop and core clock speeds are for frame rates; though there are a lot of other things that factor into FPS as well. Be sure to check the Wattage as well, GPU easily suck up the most juice over anything else.

Easier thing to do is too look at some type of comparison chart like ziek posted.
I personally used this one Graphics Card Performance Hierarchy Chart - Best Graphics Cards For The Money: July 2014 Has the fastest cards at the top, and decrease in speed as you go down. Also compares Radeon and Nvidia cards.