What is the best way to set up wireless for my gaming pc?

I am thinking about purchasing this pc: http://www.newegg.com/Product/Product.aspx?Item=N82E16883113101&nm_mc=OTC-Froogle&cm_mmc=OTC-Froogle-Desktop+PCGateway_-83113101

I have cable internet through cox. I have a wireless router downstairs, but my pc will be going upstairs. there are no cable jacks where the pc will go so I think it will have to connect wireless. should I buy a usb wireless adapter?What is a good one to buy? Are there anyother ways to connect? Will this be ok for gaming situations?

also does this computer seem good?

Thanks.