Need suggestions on a build for LoL

[HeXp Renegade]

Hey guys I was planning on buying a good gaming computer for about $1000 but now I need 2 computers for that price so $500 each. Soo I know $500 is not alot for a gaming pc, but the only game I play alot is LoL. I have two builds I found online and was wondering what would be the best combinations for my needs. https://support.leagueoflegends.com/entries/234272-system-requirements

http://newbcomputerbuild.com/newb-computer-build-home/december-2012-gaming-pc-builds/

http://www.tomshardware.com/reviews/budget-gaming-do-it-yourself-computer,3364.html

 

[HeXp Renegade]

do most games use only 2 cores?