I'm a total newbie to this, but managed to install Lubuntu on an old desktop PC.
Now I've run into an issue: the color depth isn't set to true colour (24 bit) and the gradients look super bad.

First I followed some guides to verify that the graphic card drivers are installed doing the
sudo apt-get install xserver-xorg-video-intel
thing and they are.

Then I found another guide telling me to add DefaultDepth 24 to the Xorg.conf file, but I'm not sure where to exactly put that line since it contains way more lines than the one shown in the tutorial. Here's how the config file looks like: http://pastebin.com/ufRJGbwB

Am I doing this the correct way or is there another, better way to change the color depth? Or maybe the integrated graphics aren't good enough for Lubuntu in the first place?