What processor does he have, what is his budget, what resolution is his monitor, and what game settings does he want to be able to run? Need to know all four to make a good recommendation.
In the meantime, you might also look at the THG article that lists their recommended video cards are different budget levels, it also gives a very brief blurb about what you can expect from each one they recommend. This might help you better define the budget level as well.
http://www.tomshardware.com/reviews/best-graphics-card,2964.html
For some good information about how to upgrade a video card you might also look at:
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If you budget is in the $150 to $250 range, you might look at this GTX 560 review that includes comparative stats with most of the other cards mentioned above. Make sure you read the final thoughts on the last page which summarize the author's recommendation and the performance of the cards:
http://forums.anandtech.com/showthread.php?t=2180563
Note that mainstream cards gaming are generally considered to be in the $100 to $200 range and you can find cards for less than $150 that do a credible job of running games as long as you don't turn the settings way up. Which is why we need to know the budget and other information.
A real bargain right now is the GTX 460 1 GB card which is being phased out and can now be bought for only $140 AR - and with Photsop 9 Elements thrown in:
http://www.newegg.com/Product/Produc...82E16814130570
Note that its stats are reported in the review linked higher up and the price listed there from May was $160. Not too long ago it cost almost $200.