360 arcade is crap as you will soon learn that you need hard disk... also with it you don't get headset, network cable and HD cable.
prices are as follows:
360 arcade $279
360 20 Gb $349
360 elite 120 Gb $449
PS3 40Gb $399
PS3 80GB $499
PS3 has internet browser, blu-ray, built in wireless, free online, 7.1 sound system and it's more reliable and much less noisy.
360 has better online, included headset & larger selection of games.
All in all PS3 has more to offer then 360 but 360 is a better system for gaming.