Spend 2400 Microsoft Points (that's a whopping $30!) between 12:01AM ET October 1 and 11:59PM ET October 31, and Microsoft will credit your Xbox Lvie account back 800 Points ($10) by November 30. Now, the promotion is valid on all game add-ons and XBLA titles, but we'll make the decision even easier for you: Comic Jumper + Super Meat Boy. Done. Pay me.
Update: Microsoft has notified Joystiq that the promotion is only valid on purchases of game adds-on and XBLA titles (Avatar items and other XBLM content not included).