That looks to be a standar mid-tower system case, which makes fitting a PSU easy.
500 watts is good, but 600 is better. I'll recommend a 500 watter through.
Currently, 15% off with code, and a $10 rebate. Cost : $60
CORSAIR Gaming Series GS500 500W ATX12V / EPS12V 80 PLUS Certified High Performance Gaming Power Supplyhttp://www.newegg.com/Product/Product.aspx?Item=N82E16817139033