If you get another 460,then definitely get a new monitor too, you won't see the true potential of 2 460's at your current resolution
Might as well go for a multi-monitor setup then >.>
Or he could just get a new monitor with 1920x1080 and save up for another 1680x1050 monitor later.
EVGA or Giga are fine, anythings fine but those are my choices.
Otherwise the single 460 is more than enough for most games to be played on high/max.