I've read on another thread that Lenovo has problems with its screen. I googled lenovo screen and a multitude of results returned about flickering and going black/blank. Has any lenovoite here had a problem with the screen?

I'm considering the purchase of this laptop:

http://www.saveonlaptops.co.uk/Lenovo_G570_1072020.html

How can I buy extended warranty on the laptop from that website and is it worth it? I only think it could be if there are such problems with the screen