EA's running an online holiday special for the Xbox 360 beginning Christmas that takes a quick cost-benefit analysis to figure out, but as it returns you 800 Microsoft Points might be worth considering.
The offer: Buy any three titles from this list and you get 800 Microsoft points back. Now, some of these are full $19.99 titles. But if you get a new hard drive or Christmas cash and want to lay out the price of a new game to get three, you can consider the points back to be like a gift card. And many stores run that kind of special.
If you want to know the bare minimum you can spend to still qualify, that would be buying up both Mass Effect downloads, plus the Dragon Age: Origins DLC (or Madden AFL Legacy Pack), for 1360 points. You then get 800 back, effectively making the cost 560 points, or the entire package for $7. Naturally, given the units in which Microsoft points are sold, your actual cash outlay may vary here.
The special runs from Dec. 25 to Jan. 31.