Incorrect resolution on new HP Envy 17

Hi,

I just bought this product:

http://www.hpshopping.co.nz/acquire/default.asp?pageid=custom&custom=detail&pf_id=2896950&tab=0

On the website the resolution is listed as :

17.3" diagonal High Definition HP BrightView LED Display (1366x768) Non Touch Panel

But once I started it for the first time, my resolution is 1600x900

Are the specs on the site incorrect? Should I be setting it to the lower resolution?

As the GFX card (GT740m) is optimised at 1366x768 I'm a bit confused.