Xbox 360 owners can now download any one of the three Sonic the Hedgehog themes and picture packs that are now available on Marketplace. The downloads are available to all XBL regions. The list with cost:

Sonic, Tails, and Knuckles Picture Pack - 100 pts
Shadow, Rouge, and Omega Picture Pack - 100 pts
Silver, Amy, and Blaze Picture Pack - 100 pts
Sonic's Theme 120 pts
Silver's Theme - 120 pts
Shadow's Theme - 120 pts