http://www.xbox.com/en-us/hardware/hddoffer/default.htm
Go there if you bought an Arcade Xbox 360, you can get 3 months of live free and a 20gb hard drive for 29.99$.
All you need is the serial number from your Xbox and enter that shit to get this deal. That street fighter game in HD makes it a must buy, they have Mortal Kombat 3 on Xbox Live too for 400 Microsoft points.
I just bought Rainbow 6 Las Vegas 2 that shit is aight so far, only played the first levels, got it for 20$ at Toys R Us.