Become a MacRumors Supporter for $50/year with no ads, ability to filter front page stories, and private forums.
Some of my desktops are far over 2400 and they look just as good on my 800 res MacBook Pro.

Try some of the settings in the preferences, such as fit to display or stretch. Typically, you will get better results if you at least crop the image to 16:10.
 
Register on MacRumors! This sidebar will go away, and you'll see fewer ads.