You're right to be worried.
That C-50 dual core APU @ 1.0Ghz is going to hold that notebook back.
Wow:Cat is basically a 2005 game. L4D and RE:5 are like 2008/2009 games.
There just isn't any source I could find that says how well it will run those games.
If you look at game minimum system requirements - it looks doubtful:http://www.vgrequirements.info/resident-evil-5-pc/http://www.vgrequirements.info/left-4-dead/http://www.vgrequirements.info/world-of-warcraft-pc-requirements/
Putting 8GB of RAM in there is a waste of money - even though it's not much money. Zero gain. None at all.