MacBook Pro and external monitor compatibility
The Apple 15" MacBook Pro specification about Graphics and Video Support says: 


  Dual display and video mirroring: Simultaneously supports full native
  resolution on the built-in display and up to 2560 by 1600 pixels on up
  to two external displays, at millions of colors Thunderbolt digital
  video output
  
  Native Mini DisplayPort output DVI output using Mini DisplayPort to
  DVI Adapter (sold separately) VGA output using Mini DisplayPort to VGA
  Adapter (sold separately) Dual-link DVI output using Mini DisplayPort
  to Dual-Link DVI Adapter (sold separately)