As part of my current set-up for my Raspberry Pi I am using the brilliant HDMIPi. This is billed as a “1280×800 Affordable Hi-Def HDMI screen for the Raspberry Pi”, but it could also be used for anything that outputs to HDMI.
After connecting this up for the first time I was very impressed, but this is running at 1080p and not the native 1200×800 that the LCD supports. There are some simple instructions in the HDMIPi manual to change this.
From a terminal:
sudo nano /boot/config.txt
Add the following to the end of your config.txt:
hdmi_group=2 # HDMIPi for 1280 x 800
hdmi_drive=2 # for alternative modes get sound
hdmi_mode=28 # 1280 x 800 @ 60 Hz Specifcations
Make sure that these options have not already been set in the file and then reboot the Pi.