This build focuses on using quality parts that can be used in multiple builds, and has the tools to be very good at almost any PC job. It assumes you have your own peripherals (monitor, keyboard, etc.) and are not interested in overclocking, but leaves it open should you want to try it in the future.
As for going wireless, thats easy. You can buy a $20-$40 USB stick and instantly turn any PC into a wireless PC. Or you could pick out an internal card, but that isn't my area expertise.
I am selling a very good custom built computer right now, its around that price maybe a lil bit lower, it runs every single game smoothly, like cod battle field 3 in ultra settings at 50 fps, counter strike 101 fps league of legends at 130 fps team fortress 2 at 300 fps, tell me in a pm if you are interested, i can give you the spects from the system and you can search the parts yourself to make sure you know my price is fair and good.