Which of these power supplies is best suited for my system???

Go with the Rosewill out of the two you suggested, both would work but I have experience with that brand and it is pretty good for a budget PSU. As for cases, there is a huge selection on newegg, just make sure to get one with good ventilation (at least on front and one rear fan). Try this one, best budget case I have seen:a href="http://www.newegg.com/Product/Product.asp?Item=N82E16811147038" rel="nofollow"http://www.newegg.com/Product/Product.as…/a