5.1 speakers

Hi all, I am planning to buy 5.1 speakers for my laptop/xbox360...mainly for my xbox360.. I am very confused as to which one should i buy from below mentioned speakers.. Logitech Z-5500 THX-Certified 505-Watt 5.1 Digital Surround Sound Speaker System -- $250 Logitech G51 5.1 Surround...