New to building pc need help on budget build

As the title says I'm a newb to building pc's. My current laptop is about to crap out on me and I have about $500 to spend on a pc. I have peripherals, but I would need an OS.

I'd be ok with integrated graphics at the moment, but would like to add a graphics card when I have some extra cash. If necessary to make the system handle a graphics card later on I can go up to $600. 

I would like to use the pc for school work and playing indie games, but would like to play borderlands, bioshock, and the telltale games. Any help would be appreciated.


Thank you