It's been a while since I've used PCLOS and I've just loaded it on my wifes wide screen laptop. It's the "Full Monty" so I'm not so familiar with where to find the screen size. I'm sure you can set me straight in a couple of minutes@ PCC --> Hardware --> Configure Video Card
. Pick the monitor size first, then the resolution to match. You might want to check the Graphic Card drop down menu, to be sure you are loading the best driver for the card, too.