Just a word of caution - Microsoft points considered "Promotional" (as in you got them through a contest or giveaway online) have expiration dates and can and will disappear from your account if you don't use them. Also, a reader sent us a tip that the points Microsoft used to refund people hit with the "FIFA Hack" are also these "Promotional" points, so if you don't use them up before they expire you'll lose them.
You can log in to https://billing.microsoft.com to log in with your Windows Live account and see if you have any points that will expire.
Note: This does not apply to points added to your account via point cards from retailers or points you buy with a credit card on Xbox Live. Those points won't expire. Only "Promotional" points have expiration dates.