What is a good beginners gaming PC? I only can spend about $500?

I do a lot of minecraft, gmod, portal, and octodad.

I currently own an ASUS laptop and I have no complaints, It supports high quallity games and (in my case) the screen is wide and comfortable.These days, Asus is churning out good laptops and they're decently priced too, as compared to HP or Sony, who over-charge their brand value.