I honestly can't believe MS kept the Arcade SKU, so many consumers are gonna get screwed over by it...it's not even funny.W1NGMAN-

Or 360 owners can do this as reported here on Gamespot:

UPDATE 2] After obtaining a Core 360 unit manufactured in 2005, GameSpot accessed the Upgrade site, which gives qualifying console owners two "limited time offers": a refurbished 20GB HDD for $19.99 bundled with a three-month Xbox Live Gold subscription, or a free 512MB Xbox 360 Memory Unit. The site heavily pushes the hard drive option, warning that merely grabbing the gratis memory unit "will not allow you to participate in some of the new Xbox 360 experiences" mentioned above. The offers are not consistent, however, as an attempt with a second Core unit (also bought in late 2005) only brought up the $20 HDD/3-month XBL option.