Anandtech and hardOCP are my personal favorites. The trick is to look at the articles that feature one of the top cards and compare them. For gaming, the comparison is done in frames per second (fps) as you may already know. For instance, if youre looking for a top of the line graphics card, there is an article at hardOCP about the 8800 series that also includes the X1950XTX. If you want something more economical, check out one of anandtech's gpu roundups. Also, since the systems they test on are typically based around gaming, if you look at their test setups, you might begin to get an idea of what is typical in a gaming rig with that video card. Then, the system you're thinking about might begin to take form. Hope I was at least a little helpful. Good Luck.